模板整理（持续更新）
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这篇博客整理模板 便于自己使用
另外渐渐不爱写博客 就记录写关键的模板和题目 更新不会像以前那么频繁
一维并查集：
int findx(int x)
int r=x;
while(pre[r]!=r)
r=pre[r];
int i=x;
int j;
while(pre[i]!=r)
j=pre[i];
pre[i]=r;
i=j;
return r;
int join(int x,int y)
int p1=findx(x);
int p2=findx(y);
if(p1!=p2)
pre[p2]=p1;
二维并查集：
struct xjy
int x;
int y;
;
int dir[4][2]=1,0,0,1,-1,0,0,-1;
char mmap[1111][1111];
xjy pre[1111][1111];
int num[1111][1111];
xjy findx(xjy xx)
xjy r=xx;
while(pre[r.x][r.y].x!=r.x||pre[r.x][r.y].y!=r.y)
r=pre[r.x][r.y];
xjy i=xx,j;
while(pre[i.x][i.y].x!=r.x||pre[i.x][i.y].y!=r.y)
j=pre[i.x][i.y];
pre[i.x][i.y]=r;
i=j;
return r;
void join (xjy xx,xjy yy)
xjy p1=findx(xx);
xjy p2=findx(yy);
if(p1.x!=p2.x||p1.y!=p2.y)
pre[p1.x][p1.y]=p2;
num[p2.x][p2.y]+=num[p1.x][p1.y];
num[p1.x][p1.y]=0;
带权并查集：
#include <iostream>
#include <queue>
#include <stdio.h>
#include <stdlib.h>
#include <stack>
#include <limits.h>
#include <string>
#include <string.h>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <math.h>
using namespace std;
#define maxn 100100
int pre[maxn*3+10];
int findx(int x)
int r=x;
while(pre[r]!=r)
r=pre[r];
int i=x;
int j;
while(pre[i]!=r)
j=pre[i];
pre[i]=r;
i=j;
return r;
void join(int x,int y)
int p1=findx(x);
int p2=findx(y);
if(p1!=p2)
pre[p2]=p1;
int judge(int x,int y)
int p1=findx(x);
int p2=findx(y);
if(p1==p2)
return 1;
return 0;
int main()
int t;
cin >> t;
while(t--)
for(int i=1;i<maxn*3;i++)
pre[i]=i;
int n,m;
cin >> n >> m;
for(int i=1;i<=m;i++)
char c;
int x,y;
scanf(" %c %d%d",&c,&x,&y);
if(c=='D')
join(x,y+n);
join(x+n,y);
else
if(judge(x,y+n)||judge(x+n,y))
printf("In different gangs.\\n");
else if(judge(x,y)||judge(x+n,y+n))
printf("In the same gang.\\n");
else
printf("Not sure yet.\\n");
一维树状数组
int lowbit (int x)
return x&-x;
int getsum(int x)
int sum=0;
while(x>0)
sum+=tree[x];
x-=lowbit(x);
return sum;
void add(int x,int num)
while(x<1000000)
tree[x]+=num;
x+=lowbit(x);
二维树状数组：
#include <bits/stdc++.h>
using namespace std;
int tree[1111][1111];
int book[1111][1111];
int lowbit (int x)
return x&-x;
int getsum(int x,int y)
int sum=0;
for(int i=x;i>0;i-=lowbit(i))
for(int j=y;j>0;j-=lowbit(j))
sum+=tree[i][j];
return sum;
void add(int x,int y,int num)
for(int i=x;i<=1000;i+=lowbit(i))
for(int j=y;j<=1000;j+=lowbit(j))
tree[i][j]+=num;
book[x][y]+=num;
线段树改查 dfs序：
#include <iostream>
#include <queue>
#include <stdio.h>
#include <stdlib.h>
#include <stack>
#include <limits>
#include <string>
#include <string.h>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <math.h>
using namespace std;
#define maxn 100000+5
int flag;
struct xjy
int left;
int right;
int num;
int target;
int lazy;
int sum;
int time;
;
xjy tree[maxn<<2];
vector<int > point[maxn];
int a[maxn],l[maxn],r[maxn];
int ans=0;
int cnt=1;
int remember[maxn];
int n,m;
int t;
void show(int i,int left,int right)
if(left==right)
printf("%d %d %d %d %d %d\\n",tree[i].sum,tree[i].left,tree[i].right,tree[i].lazy,tree[i].target,tree[i].time);
return;
int mid=(left+right)>>1;
show(i<<1,left,mid);
show(i<<1|1,mid+1,right);
printf("%d %d %d %d %d %d\\n",tree[i].sum,tree[i].left,tree[i].right,tree[i].lazy,tree[i].target,tree[i].time);
int ccnt=0;
void dfs(int i)
ccnt++;
l[i]=ccnt;
for(int ii=0;ii<point[i].size();ii++)
dfs(point[i][ii]);
r[i]=ccnt;
void build(int i,int left,int right)
if(left==right)
tree[i].sum=-1;
tree[i].left=left;
tree[i].right=right;
return;
int mid=(left+right)>>1;
build(i<<1,left,mid);
build(i<<1|1,mid+1,right);
tree[i].sum=-1;
tree[i].left=left;
tree[i].right=right;
void updateregion(int i,int left,int right,int ffind,int val)
if(tree[i].lazy)
tree[i].lazy=0;
if(tree[i<<1].time<tree[i].time)
tree[i<<1].lazy=1;
tree[i<<1].target=tree[i].target;
tree[i<<1].time=tree[i].time;
if(tree[i<<1|1].time<tree[i].time)
tree[i<<1|1].lazy=1;
tree[i<<1|1].target=tree[i].target;
tree[i<<1|1].time=tree[i].time;
tree[i].sum=tree[i].target;
tree[i].target=tree[i].time=0;
if(tree[i].left==left&&tree[i].right==right)
tree[i].lazy=1;
tree[i].target=val;
tree[i].time=cnt;
return;
int mid=(tree[i].left+tree[i].right)>>1;
if(right<=mid)
updateregion(i<<1,left,right,ffind,val);
else if(left>mid)
updateregion(i<<1|1,left,right,ffind,val);
else
updateregion(i<<1,left,mid,ffind,val);
updateregion(i<<1|1,mid+1,right,ffind,val);
int queryregion(int i,int ffind,int left,int right)
if(tree[i].lazy)
tree[i].lazy=0;
if(tree[i<<1].time<tree[i].time)
tree[i<<1].lazy=1;
tree[i<<1].target=tree[i].target;
tree[i<<1].time=tree[i].time;
if(tree[i<<1|1].time<tree[i].time)
tree[i<<1|1].lazy=1;
tree[i<<1|1].target=tree[i].target;
tree[i<<1|1].time=tree[i].time;
tree[i].sum=tree[i].target;
tree[i].target=tree[i].time=0;
if(tree[i].left==left&&tree[i].right==right)
//show(1,1,n);
return tree[i].sum;
int mid=(tree[i].left+tree[i].right)>>1;
if(right<=mid)
return queryregion(i<<1,ffind,left,right);
else if(left>mid)
return queryregion(i<<1|1,ffind,left,right);
else
return queryregion(i<<1,ffind,left,mid);
return queryregion(i<<1|1,ffind,mid+1,right);
扫描线：
#include <bits/stdc++.h>
using namespace std;
#define maxn 2005
struct Line
double x;
double yleft,yright;
int flag;
;
struct xjy
int left,right;
double yleft,yright;
int cnt;
double once;
double twice;
;
xjy tree[maxn<<2];
Line line[maxn];
double Hash[maxn];
bool cmp(Line a,Line b)
return a.x<b.x;
void build(int i,int left,int right)
tree[i].left=left;
tree[i].right=right;
tree[i].once=0;
tree[i].twice=0;
tree[i].yleft=Hash[left];
tree[i].yright=Hash[right];
if(left+1==right)
return ;
int mid=(left+right)>>1;
build(i<<1,left,mid);
build(i<<1|1,mid,right);
void check(int i)
if(tree[i].cnt>=2)
tree[i].once=tree[i].yright-tree[i].yleft;
tree[i].twice=tree[i].yright-tree[i].yleft;
return ;
else if(tree[i].cnt==1)
tree[i].once=tree[i].yright-tree[i].yleft;
if(tree[i].left+1==tree[i].right)
tree[i].twice=0;
else
tree[i].twice=tree[i<<1].once+tree[i<<1|1].once;
else
if(tree[i].left+1==tree[i].right)
tree[i].once=tree[i].twice=0;
else
tree[i].once=tree[i<<1].once+tree[i<<1|1].once;
tree[i].twice=tree[i<<1].twice+tree[i<<1|1].twice;
void update(int i,Line a)
if(a.yleft==tree[i].yleft&&tree[i].yright==a.yright)
tree[i].cnt+=a.flag;
check(i);
//cout << tree[i].left << tree[i].right << endl;
return;
if(a.yright<=tree[i<<1].yright)
update(i<<1,a);
else if(a.yleft>=tree[i<<1|1].yleft)
update(i<<1|1,a);
else
Line temp=a;
temp.yright=tree[i<<1].yright;
update(i<<1,temp);
temp=a;
temp.yleft=tree[i<<1|1].yleft;
update(i<<1|1,temp);
check(i);
//cout << tree[i].left << tree[i].right <<endl;
int main()
int t;
scanf("%d",&t);
for(int step=1;step<=t;step++)
int n;int cnt=1;
scanf("%d",&n);
for(int i=1;i<=n;i++)
double x1,x2,y1,y2;
scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
line[cnt].yleft=y1;
line[cnt].yright=y2;
line[cnt].x=x1;
line[cnt].flag=1;
Hash[cnt++]=y1;
line[cnt].yleft=y1;
line[cnt].yright=y2;
line[cnt].x=x2;
line[cnt].flag=-1;
Hash[cnt++]=y2;
sort(line+1,line+cnt,cmp);
sort(Hash+1,Hash+cnt);
build(1,1,cnt-1);
double ans=0;
update(1,line[1]);
for(int i=2;i<cnt;i++)
ans+=tree[1].twice*(line[i].x-line[i-1].x);
update(1,line[i]);
printf("%.2lf\\n",ans);
主席树：
#include <queue>
#include <stdio.h>
#include <map>
#include <string>
#include <iostream>
#include <string.h>
#include <stack>
#include <algorithm>
#include <set>
using namespace std;
#define maxn 100010
struct xjy
int left;
int right;
int num;
;
struct xxjy
int num;
int id;
bool operator < (const xxjy &r)const
return num<r.num;
;
xjy tree[maxn*20];
int T[maxn];
xxjy a[maxn];
int tot;
int n,m;
int build(int left,int right)
int root=tot++;
if(left==right)
tree[root].num=0;
tree[root].left=tree[root].right=0;
return root;
int mid=(left+right)>>1;
tree[root].left=build(left,mid);
tree[root].right=build(mid+1,right);
tree[root].num=0;
return root;
int update(int root,int pos,int val)
int now=tot++;
int tmp=now;
tree[now].num=tree[root].num+val;
int left=1;
int right=n;
while(left<right)
int mid=(left+right)>>1;
if(pos<=mid)
tree[now].left=tot++;
tree[now].right=tree[root].right;
root=tree[root].left;
now=tree[now].left;
right=mid;
else
tree[now].left=tree[root].left;
tree[now].right=tot++;
root=tree[root].right;
now=tree[now].right;
left=mid+1;
tree[now].num=tree[root].num+val;
return tmp;
int ans;
void query(int root,int left,int right,int l,int r)
if(left==l&&right==r)
ans+=tree[root].num;
return;
int mid=(l+r)>>1;
if(right<=mid)
query(tree[root].left,left,right,l,mid);
else if(left>mid)
query(tree[root].right,left,right,mid+1,r);
else
query(tree[root].left,left,mid,l,mid);
query(tree[root].right,mid+1,right,mid+1,r);
int main()
int t;
scanf("%d",&t);
for(int cnt=1;cnt<=t;cnt++)
printf("Case %d:\\n",cnt);
tot=0;
scanf("%d%d",&n,&m);
T[0]=build(1,n);
for(int i=1;i<=n;i++)
scanf("%d",&a[i].num),a[i].id=i;
sort(a+1,a+n+1);
for(int i=1;i<=n;i++)
T[i]=update(T[i-1],a[i].id,1);
for(int i=1;i<=m;i++)
int l,r,mid;
scanf("%d%d%d",&l,&r,&mid);
xxjy midmid;
midmid.num=mid;
midmid.id=n+1;
int time=upper_bound(a+1,a+n+1,midmid)-a-1;
ans=0;
query(T[time],l+1,r+1,1,n);
printf("%d\\n",ans);
#include <iostream>
#include <queue>
#include <stdio.h>
#include <stdlib.h>
#include <stack>
#include <limits>
#include <string>
#include <string.h>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <math.h>
using namespace std;
#define maxn 60010
struct xjy
int left;
int right;
int lmax;
int rmax;
int mmax;
;
xjy tree[maxn<<2];
int a[maxn];
int ans=0;
void build(int i,int left ,int right)
tree[i].left=left;
tree[i].right=right;
tree[i].lmax=tree[i].rmax=tree[i].mmax=right-left+1;
if(left!=right)
int mid=(left+right)>>1;
build(i<<1,left,mid);
build (i<<1|1,mid+1,right);
void updateregion(int i,int left,int right,int val)
if(tree[i].left==left&&tree[i].right==right)
tree[i].lmax=tree[i].rmax=tree[i].mmax=val;
return;
int mid=(tree[i].left+tree[i].right)>>1;
if(right<=mid)
updateregion(i<<1,left,right,val);
else if(left>mid)
updateregion(i<<1|1,left,right,val);
else
updateregion(i<<1,left,mid,val);
updateregion(i<<1|1,mid+1,right,val);
tree[i].lmax=tree[i<<1].lmax;
tree[i].rmax=tree[i<<1|1].rmax;
tree[i].mmax=max(max(tree[i<<1].mmax,tree[i<<1|1].mmax),tree[i<<1].rmax+tree[i<<1|1].lmax);
if(tree[i<<1].lmax==(tree[i<<1].right-tree[i<<1].left+1))
tree[i].lmax+=tree[i<<1|1].lmax;
if(tree[i<<1|1].rmax==(tree[i<<1|1].right-tree[i<<1|1].left+1))
tree[i].rmax+=tree[i<<1].rmax;
int query(int i,int t)
if(tree[i].left==tree[i].right||tree[i].mmax==(tree[i].right-tree[i].left+1)||!tree[i].mmax)
return tree[i].mmax;
int mid=(tree[i].left+tree[i].right)>>1;
if(t<=mid)
if(t>=tree[i<<1].right-tree[i<<1].rmax+1)
return query(i<<1,t)+query(i<<1|1,mid+1);
else
return query(i<<1,t);
else
if(t<=tree[i<<1|1].left+tree[i<<1|1].lmax-1)
return query(i<<1|1,t)+query(i<<1,mid);
else
return query(i<<1|1,t);
int main()
int n,m;
int t;
while(~scanf("%d%d",&n,&m))
for(int i=0;i<maxn;i++)
tree[i].left=0;
tree[i].lmax=0;
tree[i].mmax=0;
tree[i].right=0;
tree[i].rmax=0;
build(1,1,n);
stack<int > ss;
for(int i=1;i<=m;i++)
char s;
scanf(" %c",&s);
if(s=='D')
int mid;
scanf("%d",&mid);
updateregion(1,mid,mid,0);
ss.push(mid);
//show(1,1,n);
//printf("\\n");
else if(s=='R')
int mid;
mid=ss.top();
ss.pop();
updateregion(1,mid,mid,1);
//show(1,1,10);
else
int mid;
scanf("%d",&mid);
ans=0;
printf("%d\\n",query(1,mid));
树的遍历转化：
#include <iostream>
#include <queue>
#include <stdio.h>
#include <stdlib.h>
#include <stack>
#include <limits>
#include <string>
#include <string.h>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <math.h>
using namespace std;
int n=0;
struct tree
int val;
struct tree* l;
struct tree* r;
;
vector<int > pre;
vector<int > in;
int ii=0;
tree * after(int l,int r)
if(l>=r)
return NULL;
tree *mid = new tree;
mid->val=pre[ii++];
int m=(find(in.begin(),in.end(),mid->val)-in.begin());
mid->l=after(l,m);
mid->r=after(m+1,r);
return mid;
void show(tree* root)
if(root==NULL)
return ;
show(root->l);
show(root->r);
printf("%d ",root->val);
int main()
int n,k;
while(cin >> n)
for(int i=0;i<n;i++)
cin >> k;
in.push_back(k);
for(int i=0;i<n;i++)
cin >> k;
pre.push_back(k);
tree* root=after(0,n);
show(root);
cout << endl;
最短路：
struct xjy
int from;
int to;
int dis;
bool operator < (const xjy &r)const
return dis>r.dis;
;
vector <xjy > mmap[1000001];
vector<xjy> remember;
int dis[1000001];
int book[1000001];
int sum,q,p;
void dijkstra(int begin)
for(int i=0;i<1000000;i++)
dis[i]=INT_MAX;
book[i]=0;
priority_queue<xjy> q;
xjy mid;
mid.from=1;
mid.dis=0;
q.push(mid);
while(!q.empty())
mid=q.top();
q.pop();
if(book[mid.from])
continue;
for(int i=0;i<mmap[mid.from].size();i++)
if(!book[mmap[mid.from][i].to]&&dis[mmap[mid.from][i].to]>mid.dis+mmap[mid.from][i].dis)
book[mmap[mid.from][i].from]=1;
dis[mmap[mid.from][i].to]=mid.dis+mmap[mid.from][i].dis;
xjy midmid;
midmid.from=mmap[mid.from][i].to;
midmid.dis=dis[mmap[mid.from][i].to];
q.push(midmid);
for(int i=0;i<=p;i++)
if(dis[i]!=INT_MAX)
sum+=dis[i];
//cout << dis[i] <<" ";
kmp：
#include <string>
#include <iostream>
#include <stdio.h>
#include <vector>
#include <string.h>
#include <algorithm>
using namespace std;
int nnext[111];
char ss[111][111];
char mmid[111];
void getnext()
int i=0;
int j=-1;
nnext[0]=-1;
int len=strlen(mmid);
while(i<len)
if(j==-1||mmid[i]==mmid[j])
i++;
j++;
nnext[i]=j;
else
j=nnext[j];
int kmp(int s)
int i=0;int j=0;
int len=strlen(ss[s]);
int lenn=strlen(mmid);
getnext();
while(i<len)
if(j==-1||ss[s][i]==mmid[j])
i++;
j++;
else
j=nnext[j];
if(j==lenn)
return 1;
return 0;
最大最小表示法
最小：
[cpp] view plain copy- int getmin()
- int i=0,j=1,k=0;
- while(i<len&&j<len&&k<len)
- if(s[(i+k)%len]==s[(j+k)%len])
- k++;
- else
- if(s[(i+k)%len]>s[(j+k)%len])
- i+=k+1;
- else
- j+=k+1;
- if(i==j)
- j++;
- k=0;
- return min(i,j);
[cpp] view plain copy
- int getmax()
- int i=0,j=1,k=0;
- while(i<len&&j<len&&k<len)
- if(s[(i+k)%len]==s[(j+k)%len])
- k++;
- else
- if(s[(i+k)%len]>s[(j+k)%len])
- j+=k+1;
- else
- i+=k+1;
- if(i==j)
- j++;
- k=0;
- return min(i,j);
#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <string.h>
#include <math.h>
using namespace std;
#define maxn 22222
int n;
char s[maxn];
int c[maxn],sa[maxn],x[maxn],y[maxn],height[maxn],rrank[maxn],st[maxn][20];
void SA(int m)
for(int i=0;i<m;i++)
c[i]=0;
for(int i=0;i<n;i++)
c[x[i]=s[i]]++;
for(int i=1;i<m;i++)
c[i]+=c[i-1];
for(int i=n-1;i>=0;i--)
sa[--c[x[i]]]=i;
for(int k=1;k<=n;k<<=1)
int p=0;
for(int i=n-k;i<n;i++)
y[p++]=i;
for(int i=0;i<n;i++)
if(sa[i]>=k)
y[p++]=sa[i]-k;
for(int i=0;i<m;i++)
c[i]=0;
for(int i=0;i<n;i++)
c[x[y[i]]]++;
for(int i=1;i<m;i++)
c[i]+=c[i-1];
for(int i=n-1;i>=0;i--)
sa[--c[x[y[i]]]]=y[i];
swap(x,y);
p=1;
x[sa[0]]=0;
for(int i=1;i<n;i++)
x[sa[i]]=y[sa[i-1]]==y[sa[i]]&&y[sa[i-1]+k]==y[sa[i]+k]?p-1:p++;
if(p>=n)
break;
m=p;
void getheight()
int k=0;
for(int i=0;i<=n;i++)
rrank[sa[i]]=i;
for(int i=0;i<n;i++)
if(k)
k--;
int j=sa[rrank[i]-1];
while(s[i+k]==s[j+k])
k++;
height[rrank[i]]=k;
void ST()
for(int i=1;i<=n;i++)
st[i][0]=height[i];
for(int j=1;j<=19;j++)
for(int i=1;i+(1<<j)-1<=n;i++)
st[i][j]=min(st[i][j-1],st[i+(1<<(j-1))][j-1]);
int getmin(int x,int y)
int l=rrank[x];
int r=rrank[y];
if(l>r)
swap(l,r);
l++;
int k=log2(r-l+1);
return min(st[l][k],st[r-(1<<k)+1][k]);
三分：
#include <bits/stdc++.h>
using namespace std;
#define eps 0.0000001
struct xjy
double x;
double y;
double vx;
double vy;
;
vector<xjy > point;
int n;
double dis(double t,int now1,int now2)
return sqrt(((point[now1].x+point[now1].vx*t)-(point[now2].x+point[now2].vx*t))*
((point[now1].x+point[now1].vx*t)-(point[now2].x+point[now2].vx*t))+
((point[now1].y+point[now1].vy*t)-(point[now2].y+point[now2].vy*t))*
((point[now1].y+point[now1].vy*t)-(point[now2].y+point[now2].vy*t)));
double cal(double t)
double ans=0;
for(int i=0;i<n;i++)
for(int j=i+1;j<n;j++)
ans=max(ans,dis(t,i,j));
return ans;
double sf()
double l=0;
double r=1e8;
while((r-l)>=eps)
double mid1=(l*2+r)/3;
double mid2=(l+r*2)/3;
//cout << cal(mid2)-cal(mid1) <<endl;
if(cal(mid2)-cal(mid1)>eps)
r=mid2;
else
l=mid1;
return r;
二分图匹配：
#include<cstdio>
#include<cstring>
#include<iostream>
#include<queue>
#include<vector>
#include<cmath>
#include<algorithm>
using namespace std;
const int N=505;
int line[N][N];
int girl[N],used[N];
int k,m,n;
bool found(int x)
for(int i=1; i<=n; i++)
if(line[x][i]&&!used[i])
used[i]=1;
if(girl[i]==0||found(girl[i]))
girl[i]=x;
return 1;
return 0;
点 线：
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <queue>
#include <map>
#include <vector>
#include <set>
#include <string>
#include <math.h>
using namespace std;
const double eps = 1e-8;
int sgn(double x)
if(fabs(x) < eps)return 0;
if(x < 0)return -1;
else return 1;
struct Point
double x,y;
Point()
Point(double _x,double _y)
x = _x;y = _y;
Point operator -(const Point &b)const
return Point(x - b.x,y - b.y);
//叉积
double operator ^(const Point &b)const
return x*b.y - y*b.x;
//点积
double operator *(const Point &b)const
return x*b.x + y*b.y;
void input()
scanf("%lf%lf",&x,&y);
;
struct Line
Point s,e;
Line()
Line(Point _s,Point _e)
s = _s;e = _e;
//两直线相交求交点
//第一个值为0表示直线重合，为1表示平行，为0表示相交,为2是相交
//只有第一个值为2时，交点才有意义
pair<int,Point> operator &(const Line &b)const
Point res = s;
if(sgn((s-e)^(b.s-b.e)) == 0)
if(sgn((s-b.e)^(b.s-b.e)) == 0)
return make_pair(0,res);//重合
else return make_pair(1,res);//平行
double t = ((s-b.s)^(b.s-b.e))/((s-e)^(b.s-b.e));
res.x += (e.x-s.x)*t;
res.y += (e.y-s.y)*t;
return make_pair(2,res);
;
//判断直线和线段相交
bool Seg_inter_line(Line l1,Line l2) //判断直线l1和线段l2是否相交
return sgn((l2.s-l1.e)^(l1.s-l1.e))*sgn((l2.e-l1.e)^(l1.s-l1.e)) <= 0;
字典树
#include <iostream>
#include <string>
#include <vector>
#include <stdio.h>
#include <string.h>
using namespace std;
#define maxn 4000010
int tot;
int n;
int trie[maxn][26];
int sum[maxn];
char s[33];
void update(int root)
for(int i=0;s[i];i++)
int mid=s[i]-'a';
if(trie[root][mid]==0)
trie[root][mid]=++tot;
sum[trie[root][mid]]++;
root=trie[root][mid];
int query(int root)
int mid;
int len=strlen(s);
for(int i=0;i<len;i++)
mid=s[i]-'a';
if(trie[root][mid]==0)
return 0;
root=trie[root][mid];
return sum[root];
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