maxFlow

import std.algorithm : equal;
import std.conv : to;
struct Edge {
    int to, cap, rev;
}
void addEdge(Edge[][] g, int from, int to, int cap) {
    g[from] ~= Edge(to, cap, g[to].length.to!int);
    g[to] ~= Edge(from, 0, g[from].length.to!int-1);
}

auto g = new Edge[][](4);

addEdge(g, 0, 1, 3);
addEdge(g, 0, 2, 3);
addEdge(g, 1, 3, 2);
addEdge(g, 2, 3, 4);
auto res = maxFlow!(int, 0)(g, 0, 3);
assert(res.flow == 5);
//MinCut : S={0, 1}, T={2, 3}
assert(equal(res.dual, [false, false, true, true]));