ZOJ 3792 Romantic Value minimum cut (minimum edge number at minimum cost)

Minimum Cut and minimum cost

Edge Weight c = c * 10000 + 1

Then run a minimum cut, flow/10000 is the cost flow % 10000 is the number of edges.

This is the case where the number of edges is the least ..

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        Using namespace std; # define ll int # define N 500 # define M 205000 # define inf 107374182 # define inf64 1152921504606846976 struct Edge {ll from, to, cap, nex ;} edge [M * 2]; // note that this must be large enough. Otherwise, re will have reverse arc ll head [N], edgenum; void add (ll u, ll v, ll cap, ll rw = 0) {// if it is a directed edge, add (u, v, cap); if it is a undirected edge, add (u, v, cap, cap); Edge E = {u, v, cap, head [u]}; edge [edgenum] = E; head [u] = edgenum ++; edge E2 = {v, u, rw, head [v]}; edge [edgenum] = E2; head [v] = edgenum ++;} ll sign [N]; bool BFS (ll from, ll to) {memset (sign,-1, sizeof (sign); sign [from] = 0; queue
       
         Q; q. push (from); while (! Q. empty () {int u = q. front (); q. pop (); for (ll I = head [u]; I! =-1; I = edge [I]. nex) {ll v = edge [I]. to; if (sign [v] =-1 & edge [I]. cap) {sign [v] = sign [u] + 1, q. push (v); if (sign [to]! =-1) return true ;}}return false;} ll Stack [N], top, cur [N]; ll Dinic (ll from, ll) {ll ans = 0; while (BFS (from, to) {memcpy (cur, head, sizeof (head); ll u = from; top = 0; while (1) {if (u = to) {ll flow = inf, loc; // loc indicates the minimum cap edge in the Stack for (ll I = 0; I <top; I ++) if (flow> edge [Stack [I]. cap) {flow = edge [Stack [I]. cap; loc = I ;}for (ll I = 0; I <top; I ++) {edge [Stack [I]. c Ap-= flow; edge [Stack [I] ^ 1]. cap + = flow;} ans + = flow; top = loc; u = edge [Stack [top]. from;} for (ll I = cur [u]; I! =-1; cur [u] = I = edge [I]. nex) // cur [u] indicates the subscript if (edge [I] of the edge where the u is located. cap & (sign [u] + 1 = sign [edge [I]. to]) break; if (cur [u]! =-1) {Stack [top ++] = cur [u]; u = edge [cur [u]. to;} else {if (top = 0) break; sign [u] =-1; u = edge [Stack [-- top]. from ;}}return ans;} void init () {memset (head,-1, sizeof head); edgenum = 0;} int n, m, from,; # define dou struct int main () {int T; scanf ("% d", & T); ll I, j, u, v, d; while (T --) {init (); cin> n> m> from> to; ll all = 0; for (I = 1; I <= m; I ++) {cin> u> v> d; all + = d; d * dou + 1; add (u, v, d, d );} ll cost = Dinic (from, to); ll bian = cost % dou; cost = all-cost/dou; if (bian = 0) {puts ("Inf "); continue;} double ans = (double) cost/(double) bian; printf ("%. 2lf \ n ", ans);} return 0;}/* 99 2 0 1 2 4 5 1 41 2 11 3 12 4 23 4 22 3 1 */