uva 10330 - Power Transmission
题目大意:最大流问题。
解题思路:増广路算法加拆点。
#include <stdio.h> #include <string.h> #include <queue> using namespace std; #define min(a,b) (a)<(b)?(a):(b) const int N = 205; const int tmp = 100; const int INF = 0x3f3f3f3f; int n, g[N][N], f[N][N]; void init() { memset(g, 0, sizeof(g)); memset(f, 0, sizeof(f)); int a, b, c, t; for (int i = 1; i <= n; i++) { scanf("%d", &c); g[i + tmp][i] = c; } scanf("%d", &t); for (int i = 0; i < t; i++) { scanf("%d%d%d", &a, &b, &c); g[a][b + tmp] = c; } scanf("%d%d", &a, &b); for (int i = 0; i < a; i++) { scanf("%d", &c); g[0][c + tmp] = INF; } for (int i = 0; i < b; i++) { scanf("%d", &c); g[c][n + tmp + 1] = INF; } } int solve() { n = n + tmp + 1; int a[N], vis[N]; int ans = 0; queue<int> q; while (1) { memset(vis, 0, sizeof(vis)); memset(a, 0, sizeof(a)); int c = 0, t; vis[c] = 0; a[c] = INF; q.push(c); while (!q.empty()) { c = q.front(), q.pop(); for (int i = 0; i <= n; i++) { t = min(g[c][i] - f[c][i], a[c]); if (t > a[i]) { vis[i] = c; a[i] = t; q.push(i); } } } if (a[n] == 0) break; ans += a[n]; for (int i = n; i; i = vis[i]) { f[i][vis[i]] -= a[n]; f[vis[i]][i] += a[n]; } } return ans; } int main () { while (scanf("%d", &n) == 1) { init(); printf("%d\n", solve()); } return 0; }