[ZJOI2007]矩阵游戏

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<cmath>
  4 #include<algorithm>
  5 #include<cstring>
  6 #include<cstdlib>
  7 #include<cctype>
  8 #include<vector>
  9 #include<stack>
 10 #include<queue>
 11 using namespace std;
 12 #define enter puts("") 
 13 #define space putchar(‘ ‘)
 14 #define Mem(a) memset(a, 0, sizeof(a))
 15 typedef long long ll;
 16 typedef double db;
 17 const int INF = 0x3f3f3f3f;
 18 const db eps = 1e-8;
 19 const int maxn = 405;
 20 inline ll read()
 21 {
 22     ll ans = 0;
 23     char ch = getchar(), last = ‘ ‘;
 24     while(!isdigit(ch)) {last = ch; ch = getchar();}
 25     while(isdigit(ch)) {ans = ans * 10 + ch - ‘0‘; ch = getchar();}
 26     if(last == ‘-‘) ans = -ans;
 27     return ans;
 28 }
 29 inline void write(ll x)
 30 {
 31     if(x < 0) x = -x, putchar(‘-‘);
 32     if(x >= 10) write(x / 10);
 33     putchar(x % 10 + ‘0‘);
 34 }
 35 
 36 int t;
 37 
 38 struct Edge
 39 {
 40     int from, to, cap, flow;
 41 };
 42 vector<Edge> edges;
 43 vector<int> G[maxn];
 44 void addEdge(int from, int to)
 45 {
 46     edges.push_back((Edge){from, to, 1, 0});
 47     edges.push_back((Edge){to, from, 0, 0});
 48     int sz = edges.size();
 49     G[from].push_back(sz - 2);
 50     G[to].push_back(sz - 1);
 51 }
 52 
 53 void init()
 54 {
 55     edges.clear(); 
 56     for(int i = 0; i < maxn; ++i) G[i].clear();
 57 }
 58 
 59 int dis[maxn];
 60 bool bfs()
 61 {
 62     Mem(dis); dis[0] = 1;
 63     queue<int> q; q.push(0);
 64     while(!q.empty())
 65     {
 66         int now = q.front(); q.pop();
 67         for(int i = 0; i < (int)G[now].size(); ++i)
 68         {
 69             Edge& e = edges[G[now][i]];
 70             if(!dis[e.to] && e.cap > e.flow)
 71             {
 72                 dis[e.to] = dis[now] + 1;
 73                 q.push(e.to);
 74             }
 75         }
 76     }
 77     return dis[t];
 78 }
 79 int cur[maxn];
 80 int dfs(int now, int res)
 81 {
 82     if(now == t || res == 0) return res;
 83     int flow = 0, f;
 84     for(int& i = cur[now]; i < (int)G[now].size(); ++i)
 85     {
 86         Edge& e = edges[G[now][i]];
 87         if(dis[e.to] == dis[now] + 1 && (f = dfs(e.to, min(res, e.cap - e.flow))) > 0)
 88         {
 89             e.flow += f;
 90             edges[G[now][i] ^ 1].flow -= f;
 91             flow += f;
 92             res -= f;
 93             if(res == 0) break;
 94         }
 95     }
 96     return flow;
 97 }
 98 
 99 int maxflow()
100 {
101     int flow = 0;
102     while(bfs())
103     {
104         Mem(cur);
105         flow += dfs(0, INF);
106     }
107     return flow;
108 }
109 
110 int main()
111 {
112     int T = read();
113     while(T--)
114     {
115         init();
116         int n = read(); t = n + n + 1;
117         for(int i = 1; i <= n; ++i)
118         {
119             addEdge(0, i); addEdge(i + n, t);
120             for(int j = 1; j <= n; ++j) if(read()) addEdge(i, j + n);
121         }
122         printf("%s\n", maxflow() == n ? "Yes" : "No");
123     }
124     return 0;
125 }