平时十一测

Posted 2021-01-11 edsheeran

题解：

第一题：水题；

#include<bits/stdc++.h>
using namespace std;

const int M = 2e5 + 10;
int n, tot, k, r;

bool tag[M]; int vis[M], a[M], b[M];

bool check(int p){
    memset(vis, 0, sizeof(vis));
    memset(tag, 0, sizeof(tag));
    tot = 0;
    
    for(int i = 1; i <= p; i++) {
        vis[a[i]]++;
        if(!tag[a[i]] && vis[a[i]] >= b[a[i]]) tag[a[i]] = 1, tot++; 
    }
    if(tot == r) return 1;
    for(int i = p + 1; i <= n; i++){
        if(vis[a[i-p]] == b[a[i-p]]) tag[a[i-p]] = 0, tot--;
        vis[a[i-p]]--;
        vis[a[i]]++;
        if(!tag[a[i]] && vis[a[i]] >= b[a[i]]) tag[a[i]] = 1, tot++; 
        if(tot == r) return 1;
    }
    return 0;
    
}

int read(){
    int x=0,f=1;char c=getchar();
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
    return x*=f;
}
int main(){
    freopen("drop.in","r",stdin);
    freopen("drop.out","w",stdout);
    int T;
    scanf("%d", &T);
    while(T--){
        int x, y;
        memset(b, 0, sizeof(b));
        scanf("%d%d%d", &n, &k, &r);
        for(int i = 1; i <= n; i++) scanf("%d",&a[i]);
        for(int i = 1; i <= r; i++) {
            //scanf("%d%d", &x,&y);
            x=read();y=read();
            b[x] = y;
        }
        for(int i = 0; i <= k; i++) 
            if(!b[i]) b[i] = 2e9;
        int lf = 1, rg = n, ans = n + 1;
        while(lf <= rg){
            int mid = (lf + rg) >> 1;
            if(check(mid)) ans = mid, rg = mid - 1;
            else lf = mid + 1;
        }
        if(ans == n + 1)puts("DESTROY ALL");
        else printf("%d
", ans);
    }
}

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第二题：2—SAT；思维题；

 

 

#include<bits/stdc++.h>
using namespace std;
const int M = 4e3 + 10;
int h[M], tot;
bool vis[M];
void init(){
    memset(h, 0, sizeof(h));
    tot = 0;
}
struct edge{int v, nxt;}G[M<<1];
void add(int u, int v){
    G[++tot].v=v,G[tot].nxt=h[u],h[u]=tot;
}
void dfs(int u){
    vis[u] = 1;
    for(int i = h[u]; i; i = G[i].nxt)
        if(!vis[G[i].v]) dfs(G[i].v);
}

int main(){
    freopen("god.in","r",stdin);
    freopen("god.out","w",stdout);
    int T;
    scanf("%d", &T);
    while(T--){
        init();
        int n, m, x, y;
        scanf("%d%d", &n, &m);
        for(int i=1;i<=m;i++){
            scanf("%d%d",&x, &y);
            int xx = x > 0 ? x + n : -x;
            int yy = y > 0 ? y + n : -y;
            if(x < 0) x = -x + n;
            if(y < 0) y = -y + n;
            add(x, yy); add(y, xx); 
        }
        int ans = 3;
        for(int i = 1; i <= n; i++){
            memset(vis, 0, sizeof(vis));
            int ret = 3;
            dfs(i);
            if(vis[i + n]){
                memset(vis, 0, sizeof(vis));
                dfs(i + n);
                if(vis[i]){ans=0;continue;}
                for(int j = 1; j <= n; j++) {
                    if(vis[j]){ret=1; break;}
                }
            }
            else {
                memset(vis, 0, sizeof(vis));
                dfs(i + n);
                if(vis[i])ret=1;
                else for(int j = 1; j <= n; j++) {
                    if(vis[j]){ret=2; break;}
                }
            }
            ans = min(ans, ret);
        }
        
        if(ans == 3)puts("No Way");
        else printf("%d
", ans);
    }
    
}

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第三题：线段树+贪心+一些思维

60分

100分

 

#include<bits/stdc++.h>
using namespace std;

const int M = 5e5 + 10;
char a[M];
int n, ans[M], st[M];
struct Info{
    int sum[2];
};
struct Qu{int r, id;};
vector <Qu> q[M];

struct Node {
    Node *ls, *rs;
    Info info;
}pool[M << 2], *tail = pool, *root;
    
Info up(Info lf, Info rg){
    Info now;
    now.sum[0] = min(rg.sum[0], rg.sum[1] + lf.sum[0]); 
    now.sum[1] = lf.sum[1] + rg.sum[1];
    return now;
}

Node * build(int lf = 1, int rg = n){
    Node *nd=++tail;
    if(lf == rg){
        nd->info.sum[0]=nd->info.sum[1]=0;
    }
    else {
        int mid = (lf + rg) >> 1;
        nd->ls = build(lf, mid);
        nd->rs = build(mid + 1, rg);
        nd->info = up(nd->ls->info, nd->rs->info);
    }
    return nd;
}

#define Ls lf, mid, nd->ls
#define Rs mid+1, rg, nd->rs

Info query(int pos, int lf=1, int rg=n, Node *nd = root){
    if(lf == rg)
        return nd->info;
    
    int mid = (lf + rg) >> 1;
    if(pos <= mid) return query(pos, Ls);
    Info now = query(pos, Rs);
    now = up(nd->ls->info, now);
    return now;
    
}

void modify(int pos, int v, int lf=1, int rg=n, Node *nd = root){
    if(lf == rg)nd->info.sum[0] = nd->info.sum[1] = v;
    else {
        int mid = (lf + rg) >> 1;
        if(pos <= mid)modify(pos, v, Ls);
        else modify(pos, v, Rs);
        nd->info = up(nd->ls->info, nd->rs->info);
    }
}
int read(){
    int x=0,f=1;char c=getchar();
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
    return x*=f;
}
int main(){
    freopen("sworder.in","r",stdin);
    freopen("sworder.out","w",stdout);
    int Q;
    scanf("%d", &n);
    scanf("%s", a+1);
    scanf("%d", &Q);
    root=build();
    int tp = n + 1, l, r;
    for(int i = 1; i <= Q; i++){
        l = read(), r = read();
        q[l].push_back((Qu){r, i});
    }
    
    for(int i = n; i; i--){
        if(a[i] == ‘C‘){
            st[--tp] = i;
        }
        else {
            if(tp != n+1){
                modify(st[tp], -1);
                st[tp] = 0; tp++;
            }
            modify(i, 1);
        }
        
        for(int j=0;j<q[i].size();j++){
            int pos = upper_bound(st+tp, st+n+1, q[i][j].r) - st;
            Info ret = query(q[i][j].r);
            ans[q[i][j].id] = (pos - tp) - min(0, ret.sum[0]);
            //printf("%d %d %d %d %d   %d
", i, q[i][j].r, pos, tp, ret.sum[0]);
        }
        //printf("%d
",tp);
    }
    for(int i = 1; i <= Q; i++)printf("%d
",ans[i]);
}

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