暑假集训day7

Posted 2020-09-27 Yzyet

从今天开始，进入数据结构专场。

今天讲线段树。

第一题就好丧，调了快一天。

LA 3938

好像没什么可说的，就是细节比较多罢了

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
using namespace std;
const int maxn=500010;
inline int read(){
    int t=1,num=0;char c=getchar();
    while(c>\'9\'||c<\'0\'){if(c==\'-\')t=-1;c=getchar();}
    while(c>=\'0\'&&c<=\'9\'){num=num*10+c-\'0\';c=getchar();}
    return num*t;
}
typedef long long LL;LL a[maxn];
typedef pair<int,int>PA;
LL sum(int l,int r){return a[r]-a[l-1];}
LL sum(PA p){return sum(p.first,p.second);}
PA better(PA a,PA b){if(sum(a)!=sum(b))return sum(a)>sum(b)?a:b;return a<b?a:b;}
int askl,askr,pre[maxn],suf[maxn];PA sub[maxn];
void build(int ro,int l,int r){
    if(l==r){pre[ro]=suf[ro]=l;sub[ro]=PA(l,l);}
    else{
        int mid=(l+r)/2,lc=ro*2,rc=ro*2+1;
        build(lc,l,mid);build(rc,mid+1,r);
        LL v1=sum(l,pre[lc]);LL v2=sum(l,pre[rc]);
        if(v1==v2)pre[ro]=min(pre[lc],pre[rc]);
        else pre[ro]=v1>v2?pre[lc]:pre[rc];

        v1=sum(suf[lc],r);v2=sum(suf[rc],r);
        if(v1==v2)suf[ro]=min(suf[lc],suf[rc]);
        else suf[ro]=v1>v2?suf[lc]:suf[rc];

        sub[ro]=better(sub[lc],sub[rc]);
        sub[ro]=better(sub[ro],PA(suf[lc],pre[rc]));
    }
}
PA preq(int ro,int l,int r){
    if(pre[ro]<=askr)return PA(l,pre[ro]);
    int mid=(l+r)/2,lc=ro*2,rc=ro*2+1;
    if(askr<=mid)return preq(lc,l,mid);
    PA i=preq(rc,mid+1,r);i.first=l;
    return better(i,PA(l,pre[lc]));
}
PA sufq(int ro,int l,int r) {
    if(suf[ro]>=askl) return PA(suf[ro],r);
    int mid=(l+r)/2,lc=ro*2,rc=ro*2+1;
    if(askl>mid)return sufq(rc,mid+1,r);
    PA i=sufq(lc,l,mid);i.second=r;
    return better(i,PA(suf[rc],r));
}
PA ask(int ro,int l,int r) {
    if(askl<=l&&r<=askr)return sub[ro];
    int mid=(l+r)/2,lc=ro*2,rc=ro*2+1;
    if(askr<=mid)return ask(lc,l,mid);
    if(askl>mid)return ask(rc,mid+1,r);
    PA i1=preq(rc,mid+1,r);
    PA i2=sufq(lc,l,mid);
    PA i3=better(ask(lc,l,mid),ask(rc,mid+1,r));
    return better(PA(i2.first,i1.second),i3);
}
int main(){
    int cnt=0,n,q;
    while(scanf("%d%d",&n,&q)==2) {
        a[0]=0;for(int i=1;i<=n;i++)a[i]=a[i-1]+read();
        build(1,1,n);printf("Case %d:\\n",++cnt);
        while(q--){
            askl=read();askr=read();
            PA ans=ask(1,1,n);
            printf("%d %d\\n",ans.first,ans.second);
        }
    }
    return 0;
}

RMQ with shift(UVa 12299)

线段树挺简单的、关键就是读入

我用一个快读，直接把字符忽略掉了。

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int maxn=100010;
const int INF=947483647;
inline int read(){
    int t=1,num=0;char c=getchar();
    while(c>\'9\'||c<\'0\'){if(c==\'-\')t=-1;if(c==\'\\n\')return INF;c=getchar();}
    while(c>=\'0\'&&c<=\'9\'){num=(num<<3)+(num<<1)+c-\'0\';c=getchar();}
    return num*t;
}
int n,q,a[maxn],t[3*maxn];
void build(int ro,int l,int r){
    if(l==r)t[ro]=a[l];
    else{
        int mid=(l+r)/2;
        build(ro*2,l,mid);build(ro*2+1,mid+1,r);
        t[ro]=min(t[ro*2],t[ro*2+1]);
    }
}
int ask(int ro,int l,int r,int x,int y){
    if(x>r||y<l) return INF;
    if(x<=l&&r<=y) return t[ro];
    int mid=(l+r)/2;
    return min(ask(ro*2,l,mid,x,y),ask(ro*2+1,mid+1,r,x,y));
}
void change(int ro,int l,int r,int x,int add){
    if(l==r){if(x==l){t[ro]=add;}return;}
    int mid=(l+r)/2;
    if(x<=mid)change(ro*2,l,mid,x,add);
    else  change(ro*2+1,mid+1,r,x,add);
    t[ro]=min(t[ro*2],t[ro*2+1]);
}
int main()
{
    n=read();q=read();
    for(int i=1;i<=n;i++)a[i]=read();
    build(1,1,n);
    for(int i=1;i<=q;i++){
        char c=getchar();while(c!=\'s\'&&c!=\'q\')c=getchar();
        if(c==\'q\'){
            int x=read(),y=read();
            printf("%d\\n",ask(1,1,n,x,y));
        }
        else{
            int x=read(),y=read();
            int f=a[x];
            while(y!=INF){
                change(1,1,n,x,a[y]);a[x]=a[y];
                x=y;y=read();
            }change(1,1,n,x,f);a[x]=f;
        }
    }
    return 0;
}

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