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84 lines
2.0 KiB
84 lines
2.0 KiB
#include <bits/stdc++.h>
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using namespace std;
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typedef long long LL;
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const int N = 510, M = 10010;
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int n, m;
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struct Edge {
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int a, b, w;
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bool f;
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bool operator<(const Edge &t) const {
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return w < t.w;
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}
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} edge[M];
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int p[N];
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int dist1[N][N], dist2[N][N];
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int h[N], e[N * 2], w[N * 2], ne[N * 2], idx;
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void add(int a, int b, int c) {
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e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx++;
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}
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int find(int x) {
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if (x == p[x]) return x;
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return p[x] = find(p[x]);
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}
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void dfs(int u, int fa, int maxd1, int maxd2, int d1[], int d2[]) {
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d1[u] = maxd1, d2[u] = maxd2;
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for (int i = h[u]; ~i; i = ne[i]) {
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int j = e[i];
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if (j != fa) {
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int td1 = maxd1, td2 = maxd2;
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if (w[i] > td1)
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td2 = td1, td1 = w[i];
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else if (w[i] < td1 && w[i] > td2)
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td2 = w[i];
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dfs(j, u, td1, td2, d1, d2);
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}
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}
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}
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int main() {
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scanf("%d%d", &n, &m);
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memset(h, -1, sizeof h);
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for (int i = 0; i < m; i++) {
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int a, b, w;
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scanf("%d%d%d", &a, &b, &w);
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edge[i] = {a, b, w};
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}
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sort(edge, edge + m);
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for (int i = 1; i <= n; i++) p[i] = i;
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LL sum = 0;
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for (int i = 0; i < m; i++) {
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int a = edge[i].a, b = edge[i].b, w = edge[i].w;
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int pa = find(a), pb = find(b);
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if (pa != pb) {
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p[pa] = pb;
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sum += w;
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add(a, b, w), add(b, a, w);
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edge[i].f = true;
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}
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}
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for (int i = 1; i <= n; i++) dfs(i, -1, -1e9, -1e9, dist1[i], dist2[i]);
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LL res = 1e18;
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for (int i = 0; i < m; i++)
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if (!edge[i].f) {
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int a = edge[i].a, b = edge[i].b, w = edge[i].w;
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LL t;
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if (w > dist1[a][b])
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t = sum + w - dist1[a][b];
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else if (w > dist2[a][b])
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t = sum + w - dist2[a][b];
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res = min(res, t);
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}
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printf("%lld\n", res);
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return 0;
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}
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