一看就是网络流,直接上Dinic模板,交上,RE,把MAXM改成500,过了,对出题者无语!
/*
* hdu1532/win.cpp
* Created on: 2011-10-5
* Author : ben
*/
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <queue>
using namespace std;
typedef long long typec;
const typec inf = 0x7fffffffffffffffLL;
const int MAXE = 510;
const int MAXN = 210;
typedef struct {
int x, y, nxt;
typec c;
} Edge;
Edge bf[MAXE];
int ne, head[MAXN], cur[MAXN], ps[MAXN], dep[MAXN];
void addedge(int x, int y, typec c) {
bf[ne].x = x;
bf[ne].y = y;
bf[ne].c = c;
bf[ne].nxt = head[x];
head[x] = ne++;
bf[ne].x = y;
bf[ne].y = x;
bf[ne].c = 0;
bf[ne].nxt = head[y];
head[y] = ne++;
}
typec flow(int n, int s, int t) {
typec tr, res = 0;
int i, j, k, f, r, top;
while (1) {
memset(dep, -1, n * sizeof(int));
for (f = dep[ps[0] = s] = 0, r = 1; f != r;) {
for (i = ps[f++], j = head[i]; j; j = bf[j].nxt) {
if (bf[j].c && -1 == dep[k = bf[j].y]) {
dep[k] = dep[i] + 1;
ps[r++] = k;
if (k == t) {
f = r;
break;
}
}
}
}
if (-1 == dep[t]) {
break;
}
memcpy(cur, head, n * sizeof(int));
for (i = s, top = 0;;) {
if (i == t) {
for (k = 0, tr = inf; k < top; ++k) {
if (bf[ps[k]].c < tr) {
tr = bf[ps[f = k]].c;
}
}
for (k = 0; k < top; k++) {
bf[ps[k]].c -= tr, bf[ps[k] ^ 1].c += tr;
}
res += tr;
i = bf[ps[top = f]].x;
}
for (j = cur[i]; cur[i]; j = cur[i] = bf[cur[i]].nxt) {
if (bf[j].c && dep[i] + 1 == dep[bf[j].y]) {
break;
}
}
if (cur[i]) {
ps[top++] = cur[i];
i = bf[cur[i]].y;
} else {
if (0 == top) {
break;
}
dep[i] = -1;
i = bf[ps[--top]].x;
}
}
}
return res;
}
int main() {
#ifndef ONLINE_JUDGE
freopen("data.in", "r", stdin);
#endif
int n, m;
int a, b;
long long c;
while (scanf("%d%d", &m, &n) == 2) {
ne = 2;
memset(head, 0, sizeof(head));
for (int i = 0; i < m; i++) {
scanf("%d%d%I64d", &a, &b, &c);
addedge(a - 1, b - 1, c);
}
printf("%I64d\n", flow(n, 0, n - 1));
}
return 0;
}