POJ1459 最大网络流

  1 //Memory: 292K        Time: 391MS
  2 #include <iostream>
  3 #include <cstring>
  4 
  5 using namespace std;
  6 
  7 const int maxn = 110;
  8 int c[maxn][maxn];
  9 int cf[maxn][maxn];
 10 int p[maxn], cc[maxn];
 11 int n, np, nc, m;
 12 int u, v, l;
 13 int edge[maxn][maxn];
 14 int ne[maxn];
 15 int prior[maxn];
 16 char in[30];
 17 const int s = 101;
 18 int q[maxn];
 19 int front, rear;
 20 bool vis[maxn];
 21 int consume;
 22 
 23 bool bfs( int s )
 24 {
 25     for (int i = 0; i <= n; i++)
 26         prior[i] = -1;
 27     front = rear = 0;
 28     q[rear++] = s;
 29     while (front != rear) {
 30         int current = q[front++];
 31         if ( cf[current][n] > 0 ) {
 32             prior[n] = current;
 33             return true;;
 34         }
 35         for (int i = 0; i < ne[current]; i++) {
 36             if (cf[current][edge[current][i]] > 0 && edge[current][i] != current && prior[ edge[current][i] ] == -1 ) {
 37                 prior[ edge[current][i] ] = current;
 38                 q[rear++] = edge[current][i];
 39             }
 40         }
 41     }
 42     return false;
 43 }
 44 
 45 void update()
 46 {
 47     int current;
 48     int pr = n;
 49     int _min = 1010;
 50     while ( pr != s ) {
 51         current = pr;
 52         pr = prior[current];
 53         if ( cf[pr][current] < _min)
 54             _min = cf[pr][current];
 55     }
 56     current;
 57     pr = n;
 58     while (pr != s) {
 59         current = pr;
 60         pr = prior[current];
 61         cf[pr][current] -= _min;
 62         cf[current][pr] += _min;
 63     }
 64     consume += _min;
 65 }
 66 
 67 void input()
 68 {
 69     memset(c, 0, sizeof(c));
 70     memset(edge, 0, sizeof(edge));
 71     memset(ne, 0, sizeof(ne));
 72         for (int i = 0; i < m; i++){
 73             scanf("%s", in);
 74             int ix;
 75             u = 0;
 76             for (ix = 1; in[ix] != ‘,‘; ix++)
 77                 u = u * 10 + in[ix] - ‘0‘;
 78             v = 0;
 79             for (ix++; in[ix] != ‘)‘; ix++)
 80                 v = v * 10 + in[ix] - ‘0‘;
 81             l = 0;
 82             int len = strlen(in);
 83             for (ix++; ix < len; ix++) {
 84                 l = l * 10 + in[ix] - ‘0‘;
 85             }
 86             c[u][v] = l;
 87             edge[u][ne[u]++] = v;
 88         }
 89         for (int i = 0; i < np; i++) {
 90             scanf("%s", in);
 91             int ix;
 92             u = 0;
 93             for (ix = 1; in[ix] != ‘)‘; ix++)
 94                 u = u * 10 + in[ix] - ‘0‘;
 95             l = 0;
 96             int len = strlen(in);
 97             for (ix++; ix < len; ix++) {
 98                 l = l * 10 + in[ix] - ‘0‘;
 99             }
100             c[s][u] = l;
101             edge[s][ne[s]++] = u;
102         }
103         for (int i = 0; i < nc; i++) {
104             scanf("%s", in);
105             int ix;
106             u = 0;
107             for (ix = 1; in[ix] != ‘)‘; ix++)
108                 u = u * 10 + in[ix] - ‘0‘;
109             l = 0;
110             int len = strlen(in);
111             for (ix++; ix < len; ix++) {
112                 l = l * 10 + in[ix] - ‘0‘;
113             }
114             c[u][n] = l;
115             edge[u][ne[u]++] = n;
116         }
117 }
118 int main()
119 {
120     while ( scanf("%d%d%d%d", &n, &np, &nc, &m) != EOF ){
121         input();
122         memcpy(cf, c, sizeof(c));
123         consume = 0;
124         while ( bfs(s) ) {
125             update();
126         }
127         printf("%d\n", consume);
128     }
129     return 0;
130 }