【题目链接】
【思路要点】
- 补档博客，无题解。
【代码】
#include<bits/stdc++.h> using namespace std; #define MAXN 505 #define MAXP 300005 #define INF 1e9 template <typename T> void read(T &x) { x = 0; int f = 1; char c = getchar(); for (; !isdigit(c); c = getchar()) if (c == '-') f = -f; for (; isdigit(c); c = getchar()) x = x * 10 + c - '0'; x *= f; } struct edge {int dest, flow; unsigned home; }; int n, m, s, t, tot; int dist[MAXP]; unsigned curr[MAXP]; vector <edge> a[MAXP]; bool bfs() { memset(dist, 0, sizeof(dist)); static int q[MAXP]; int l = 0, r = 0; dist[s] = 1, q[0] = s; while (l <= r) { int tmp = q[l++]; for (unsigned i = 0; i < a[tmp].size(); i++) if (a[tmp][i].flow != 0 && dist[a[tmp][i].dest] == 0) { dist[a[tmp][i].dest] = dist[tmp] + 1; q[++r] = a[tmp][i].dest; } } return dist[t] != 0; } int dinic(int pos, int limit) { if (pos == t) return limit; int used = 0, tmp; for (unsigned &i = curr[pos]; i < a[pos].size(); i++) if (a[pos][i].flow != 0 && dist[pos] + 1 == dist[a[pos][i].dest] && (tmp = dinic(a[pos][i].dest, min(limit - used, a[pos][i].flow)))) { used += tmp; a[pos][i].flow -= tmp; a[a[pos][i].dest][a[pos][i].home].flow += tmp; if (used == limit) return limit; } return used; } void addedge(int s, int t, int flow) { a[s].push_back((edge) {t, flow, a[t].size()}); a[t].push_back((edge) {s, 0, a[s].size() - 1}); } int main() { read(n); s = 0, t = tot = n + 1; int ans = 0; for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) { int x; read(x); ans += x; addedge(++tot, t, x); addedge(i, tot, INF); addedge(j, tot, INF); } for (int i = 1; i <= n; i++) { int x; read(x); addedge(s, i, x); } while (bfs()) { memset(curr, 0, sizeof(curr)); ans -= dinic(s, INF); } cout << ans << endl; return 0; }