101 lines
2.5 KiB
C++
101 lines
2.5 KiB
C++
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <math.h>
|
|
#include <string.h>
|
|
#include <string>
|
|
#include <vector>
|
|
#include <map>
|
|
#include <set>
|
|
#include <queue>
|
|
#include <algorithm>
|
|
#include <iostream>
|
|
#include <sstream>
|
|
using namespace std;
|
|
const int maxn = 2505;
|
|
struct Graph {
|
|
int hed[maxn], pnt[maxn*2], val[maxn*2], nxt[maxn*2], cnt;
|
|
void init(int n) {
|
|
cnt = 0;
|
|
memset(hed, -1, 4 * n);
|
|
}
|
|
void addedge(int x, int y, int v) {
|
|
pnt[cnt] = y; val[cnt] = v; nxt[cnt] = hed[x]; hed[x] = cnt++;
|
|
pnt[cnt] = x; val[cnt] = v; nxt[cnt] = hed[y]; hed[y] = cnt++;
|
|
}
|
|
} g;
|
|
queue<int> Q;
|
|
int n;
|
|
int banx, bany;
|
|
int par[maxn], dis[maxn];
|
|
int xx, yy;
|
|
int bfs(int x) {
|
|
int ret = x;
|
|
dis[x] = 0;
|
|
Q.push(x);
|
|
while (!Q.empty()) {
|
|
int a = Q.front();
|
|
Q.pop();
|
|
for (int p = g.hed[a]; p != -1; p = g.nxt[p]) {
|
|
int b = g.pnt[p];
|
|
if (dis[b] != -1) continue;
|
|
if (a == banx && b == bany || a == bany && b == banx) continue;
|
|
par[b] = a;
|
|
dis[b] = dis[a] + g.val[p];
|
|
Q.push(b);
|
|
if (dis[b] > dis[ret]) ret = b;
|
|
}
|
|
}
|
|
return ret;
|
|
}
|
|
void FindRoad(int x) {
|
|
memset(par, -1, 4 * n);
|
|
memset(dis, -1, 4 * n);
|
|
yy = bfs(x);
|
|
memset(par, -1, 4 * n);
|
|
memset(dis, -1, 4 * n);
|
|
xx = bfs(yy);
|
|
}
|
|
int ans;
|
|
vector<int> v, d;
|
|
void Solve() {
|
|
int t, disx, disy, disedge, dxx, dyy;
|
|
banx = bany = -1;
|
|
FindRoad(0);
|
|
v.clear(); d.clear();
|
|
t = xx;
|
|
while (true) {
|
|
v.push_back(t);
|
|
t = par[t];
|
|
if (t == -1) break;
|
|
d.push_back(dis[v.back()] - dis[t]);
|
|
}
|
|
ans = dis[xx];
|
|
for (int i = 1; i < v.size(); i++) {
|
|
banx = v[i-1]; bany = v[i];
|
|
disedge = d[i-1];
|
|
FindRoad(banx);
|
|
dxx = disx = dis[xx];
|
|
for (t = xx; t != -1; t = par[t])
|
|
disx = min(disx, max(dis[xx] - dis[t], dis[t]));
|
|
FindRoad(bany);
|
|
dyy = disy = dis[xx];
|
|
for (t = xx; t != -1; t = par[t])
|
|
disy = min(disy, max(dis[xx] - dis[t], dis[t]));
|
|
ans = min(ans, max(max(disx + disy + disedge, dxx), dyy));
|
|
}
|
|
}
|
|
int main() {
|
|
int t, x, y, v, i, cas = 1;
|
|
for (scanf("%d", &t); t--; ) {
|
|
scanf("%d", &n);
|
|
g.init(n);
|
|
for (i = 1; i < n; i++) {
|
|
scanf("%d %d %d", &x, &y, &v);
|
|
g.addedge(x, y, v);
|
|
}
|
|
Solve();
|
|
printf("Case %d: %d\n", cas++, ans);
|
|
}
|
|
return 0;
|
|
}
|