POJ 1273 Drainage Ditches 最大流

很裸的最大流问题，不过注意会有重边，o(╯□╰)o，被阴了WA了一发 还有就是要用long long

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>using namespace std;typedef long long LL;
const int maxn = 205;
const int maxm = 205;
const int INF = INT_MAX / 2;
LL flow[maxn][maxn],C[maxn][maxn];
int n,m;void input() {memset(C,0,sizeof(C));for(int i = 1;i <= m;i++) {int a,b,c; scanf("%d%d%d",&a,&b,&c);C[a][b] += c;}
}LL alpha[maxn];
int pre[maxn];
int q[maxn + 20],qs,qe;void solve() {int s = 1,t = n;memset(flow,0,sizeof(flow));while(1) {for(int i = s + 1;i <= t;i++) pre[i] = -2;pre[s] = -1;qs = 0; qe = 1; q[qs] = s;alpha[s] = 1e13;while(qs < qe && pre[t] == -2) {int v = q[qs]; qs++;for(int i = s;i <= t;i++) {if(pre[i] == -2 && C[v][i] - flow[v][i] != 0) {alpha[i] = min(alpha[v],C[v][i] - flow[v][i]);pre[i] = v;q[qe++] = i;}}}if(pre[t] == -2) break;for(int i = t;pre[i] != -1;i = pre[i]) {flow[pre[i]][i] += alpha[t];flow[i][pre[i]] = -flow[pre[i]][i];}}LL ans = 0;for(int i = s;i < t;i++) ans += flow[i][t];printf("%lld\n",ans);
}int main() {while(scanf("%d%d",&m,&n) != EOF) {input();solve();}return 0;
}