POJ3436 Command Network [最小树形图]
POJ3436 Command Network
最小树形图裸题
傻逼poj回我青春
wa wa wa 的原因竟然是需要%.2f
而不是.2lf
我还有英语作业音乐作业写不完了啊啊啊啊啊啊啊啊啊
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <vector>
#define fir first
#define sec second
using namespace std;
const int N = 1005, M = 1e6+5, inf = 1e9+7;
int n, m, x[N], y[N];
struct edge {
int u, v;
double w;
} e[M];
inline double dis(int u, int v) {
return sqrt((x[u]-x[v])*(x[u]-x[v]) + (y[u]-y[v])*(y[u]-y[v]));
}
pair<double, int> fa[N];
int vis[N], id[N];
double zhu_liu(int root = 1) {
double ans = 0;
while(true) {
for(int i=1; i<=n; i++) fa[i] = make_pair(inf, 0);
for(int i=1; i<=m; i++) {
int u = e[i].u, v = e[i].v;
fa[v] = min(fa[v], make_pair(e[i].w, u));
}
for(int i=1; i<=n; i++) if(i != root && !fa[i].sec) {
return -1;
}
fa[root] = make_pair(0, 0);
memset(vis, 0, sizeof(vis));
memset(id, 0, sizeof(id));
int num = 0;
for(int i=1; i<=n; i++) if(i != root) {
ans += fa[i].fir;
int u = i;
while(u != root && !vis[u]) vis[u] = i, u = fa[u].sec;
if(u != root && vis[u] == i) {
num++;
while(id[u] != num) id[u] = num, u = fa[u].sec;
}
}
if(!num) break;
for(int i=1; i<=n; i++) if(!id[i]) id[i] = ++num;
int cnt = 0;
for(int i=1; i<=m; i++) {
int u = e[i].u, v = e[i].v;
double tmp = fa[v].fir;
u = id[u];
v = id[v];
if(u == v) continue;
e[++cnt] = (edge) {u, v, e[i].w - tmp};
}
n = num;
m = cnt;
root = id[root];
}
return ans;
}
int main() {
//ios::sync_with_stdio(false); cin.tie(); cout.tie();
while(cin >> n >> m) {
for(int i=1; i<=n; i++) scanf("%d %d", &x[i], &y[i]);
int cnt = 0;
for(int i=1; i<=m; i++) {
int u, v;
scanf("%d %d", &u, &v);
if(u == v) continue;
e[++cnt] = (edge) {u, v, dis(u, v)};
}
m = cnt;
double ans = zhu_liu();
if(ans == -1) puts("poor snoopy");
else printf("%.2f\n", ans);
}
}
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