Алгоритм Форда-Фалкерсона
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#include <stdio.h>
#include <algorithm>
#include <vector>
using namespace std;
struct Edge {
int a, b, cap, flow;
Edge(int a, int b, int cap) : a(a), b(b), cap(cap), flow(0) {}
int other(int v) {
return v == a ? b : a;
}
int capTo(int v) {
return v == b ? cap - flow : flow;
}
void addFlowTo(int v, int f) {
flow += (v == b ? f : -f);
}
};
vector<Edge> edges;
int n, m, u[1010], p[1010];
vector<int> g[1010];
bool dfs(int v, int vTarget) {
u[v] = 1;
if (v == vTarget)
return 1;
for (int i = 0; i < g[v].size(); i++) {
int e = g[v][i], to = edges[e].other(v);
if (!u[to] && edges[e].capTo(to)) {
p[to] = e;
if (dfs(to, vTarget))
return 1;
}
}
return 0;
}
int main() {
scanf("%d%d", &n, &m);
int a, b, cap;
for (int i = 0; i < m; i++) {
scanf("%d%d%d", &a, &b, &cap);
edges.push_back(Edge(a - 1, b - 1, cap));
g[a - 1].push_back(edges.size() - 1);
g[b - 1].push_back(edges.size() - 1);
}
int flow = 0;
while (1) {
fill(u, u + n, 0);
if (!dfs(0, n - 1))
break;
int deltaFlow = 1 << 30;
for (int v = n - 1; v != 0; v = edges[p[v]].other(v))
deltaFlow = min(deltaFlow, edges[p[v]].capTo(v));
flow += deltaFlow;
for (int v = n - 1; v != 0; v = edges[p[v]].other(v))
edges[p[v]].addFlowTo(v, deltaFlow);
}
printf("%d", flow);
}