add MinCostMaxFlow.cpp

Author: AmazingCaddy

template/Graph/NetworkFlow_SAP.cpp template/Graph/MaxFlow_SAP.cpp

@@ -0,0 +1,96 @@
+// 最小费用最大流，增加S，T，容量为2
+// pku 2135
+#include <iostream>
+#include <stdio.h>
+#include <algorithm>
+#include <ctime>
+
+using namespace std;
+
+const int maxn = 2005;
+const int maxm = 100005;
+const int inf = 0x2f2f2f2f;
+
+int n, m;
+int d[maxn], q[65537], v[maxn], pre[maxn], preh[maxn];
+int vpt[maxm], next[maxm], head[maxm], flow[maxm], cost[maxm];
+int l = 1;
+
+void add (int a, int b, int f, int c) {
+	vpt[++ l] = b;
+	next[l] = head[a];
+	head[a] = l;
+	flow[l] = f;
+	cost[l] = c;
+	vpt[++ l] = a;
+	next[l] = head[b];
+	head[b] = l;
+	flow[l] = 0;
+	cost[l] = -c;
+}
+
+int spfa (int n, int s, int t) {
+	int i, l, r;
+	for (i = 0; i < n; ++ i)
+		d[i] = inf, v[i] = 0;
+	d[q[l = 0] = s] = 0;
+	r = 1;
+	while (l ^ r) {
+		int x = q[l ++];
+		l &= 65535;
+		v[x] = 0;
+		for (i = head[x]; i; i = next[i]) {
+			int y = vpt[i];
+			if (flow[i] > 0 && d[x] + cost[i] < d[y]) {
+				d[y] = d[x] + cost[i];
+				pre[y] = x;
+				preh[y] = i;
+				if (!v[y])
+					q[r ++] = y, v[y] = 1, r &= 65535;
+			}
+		}
+	}
+	return d[t];
+}
+
+int mincostmaxflow (int n, int s, int t, int &f_ans) {
+	int ans = 0, i, f;
+	f_ans = 0;
+	while (true) {
+		f = spfa(n, s, t);
+		if (f == inf)
+			break;
+		ans += f;
+		f = inf;
+		for (i = t; i != s; i = pre[i])
+			f = min(f, flow[preh[i]]);
+		f_ans += f;
+		for (i = t; i != s; i = pre[i])
+			flow[preh[i]] -= f, flow[preh[i] ^ 1] += f;
+	}
+	return ans;
+}
+
+void init (int n) {
+	l = 1;
+	int i;
+	for (i = 0; i < n; ++ i)
+		head[i] = 0;
+}
+
+int main () {
+	int i, j, t, m, n, u, v, r, s, a, b, c;
+	while (scanf("%d%d", &n, &m) != EOF) {
+		init(n + 2);
+		add(0, 1, 2, 0);
+		add(n, n + 1, 2, 0);
+		while (m --) {
+			scanf("%d%d%d", &a, &b, &c);
+			add(a, b, 1, c);
+			add(b, a, 1, c);
+		}
+		s = mincostmaxflow(n + 2, 0, n + 1, t);
+		printf("%d\n", s);
+	}
+	return 0;
+}