49 lines
1.3 KiB
C++
49 lines
1.3 KiB
C++
#include <bits/stdc++.h>
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#define int long long
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using namespace std;
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int n;
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int p[100005];
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vector<int> fri[100005];
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long double k;
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int bc[100005];
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int find(int now) {
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if(bc[now] == now) return now;
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return bc[now] = find(bc[now]);
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}
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int dps[100005][2], dpt[100005][2];
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void dfs(int now, bool s, int from) {
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if(s) dps[now][1] = p[now];
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else dpt[now][1] = p[now];
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if(s && now == T) dps[now][1] = LLONG_MIN;
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else if(!s && now == S) dpt[now][1] = LLONG_MIN;
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for(int i:fri[now]) {
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if(i == from) continue;
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dfs(i, s, now);
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if(s) dps[now][1] += dps[i][0], dps[now][0] += max(dps[i][0], dps[i][1]);
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else dpt[now][1] += dpt[i][0], dpt[now][0] += max(dpt[i][0], dpt[i][1]);
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}
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}
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signed main() {
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int S, T;
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scanf("%lld", &n);
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for(int i = 0; i < n; ++i) {
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scanf("%lld", &p[i]);
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bc[i] = i;
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}
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for(int i = 0, u, v; i < n; ++i) {
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scanf("%lld%lld", &u, &v);
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if(find(u) == find(v)) {
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S = u, T = v;
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} else {
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fri[u].push_back(v);
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fri[v].push_back(u);
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bc[find(u)] = find(v);
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}
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}
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scanf("%llf", &k);
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dfs(S, 1, -1);
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dfs(T, 0, -1);
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int ans = max(max(dps[S][0], dps[S][1]), max(dpt[T][1], dpt[T][0]));
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printf("%.1llf\n", ans * k);
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return 0;
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} |