1433: [ZJOI2009]假期的宿舍

1433: [ZJOI2009]假期的宿舍

链接

分析：

　　直接网络流，看是否满足即可。

　　S向每个有需要的人连边，有床的向T连边，认识的人之间互相连边。

代码：

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<iostream>
#include<cmath>
#include<cctype>
#include<set>
#include<queue>
#include<vector>
#include<map>
using namespace std;
typedef long long LL;

inline int read() {
    int x=0,f=1;char ch=getchar();for(;!isdigit(ch);ch=getchar())if(ch=='-')f=-1;
    for(;isdigit(ch);ch=getchar())x=x*10+ch-'0';return x*f;
}

const int N = 105, INF = 1e9;
struct Edge { int to, nxt, cap; } e[50005];
int head[N], dis[N], cur[N], q[N], a[N];
int S, T, En;

inline void add_edge(int u,int v,int w) {
    ++En; e[En].to = v, e[En].cap = w, e[En].nxt = head[u]; head[u] = En;
    ++En; e[En].to = u, e[En].cap = 0, e[En].nxt = head[v]; head[v] = En;
}
bool bfs() {
    for (int i = 0; i <= T; ++i) cur[i] = head[i], dis[i] = -1;
    int L = 1, R = 0;
    q[++R] = S; dis[S] = 0; 
    while (L <= R) {
        int u = q[L ++];
        for (int i = head[u]; i; i = e[i].nxt) {
            int v = e[i].to;
            if (dis[v] == -1 && e[i].cap > 0) {
                dis[v] = dis[u] + 1;
                q[++R] = v;
                if (v == T) return true;
            }
        }
    }
    return false;
}
int dfs(int u,int flow) {
    if (u == T) return flow;
    int used = 0;
    for (int &i = cur[u]; i; i = e[i].nxt) {
        int v = e[i].to;
        if (dis[v] == dis[u] + 1 && e[i].cap > 0) {
            int tmp = dfs(v, min(flow - used, e[i].cap));
            if (tmp > 0) {
                used += tmp, e[i].cap -= tmp, e[i ^ 1].cap += tmp;
                if (used == flow) break;
            }
        }
    }
    if (used != flow) dis[u] = -1;
    return used;
}
int dinic() {
    int ans = 0;
    while (bfs()) ans += dfs(S, INF);
    return ans;
}
void solve() {
    En = 1;memset(head, 0, sizeof(head));
    int n = read(), tot = 0;
    S = 0, T = n + n + 1;
    for (int i = 1; i <= n; ++i) {
        a[i] = read();
        if (a[i]) add_edge(i + n, T, 1);
    }
    for (int i = 1; i <= n; ++i) {
        int x = read();
        if ((a[i] && !x) || !a[i]) add_edge(S, i, 1), tot ++;
    }
    for (int i = 1; i <= n; ++i) 
        for (int j = 1; j <= n; ++j) {
            int x = read();
            if (x || i == j) add_edge(i, j + n, 1);
        }
    if (dinic() == tot) puts("^_^");
    else puts("T_T");    
}
int main() {
    for (int Case = read(); Case --; solve());
    return 0;
}