METO CODE 223 拉力赛
继续水板子题...
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#include <bits/stdc++.h> #define ll long long using namespace std; inline int read() { int x = 0, f = 1; char ch = getchar(); while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); } while (ch >= '0' && ch <= '9') { x = x * 10 + ch - '0'; ch = getchar(); } return x * f; } const int maxn = 5e5 + 10; struct Edge { int to, next, c; } edge[maxn]; int cnt, head[maxn]; struct Qedge { int to, next; } qedge[maxn]; int qcnt, qhead[maxn], n, m; int lca[maxn]; ll dep[maxn]; int par[maxn]; int temp[maxn]; bool vis[maxn]; inline void addedge(int u, int v, int c) { edge[++cnt].to = v; edge[cnt].c = c; edge[cnt].next = head[u]; head[u] = cnt; } inline void addqedge(int u, int v) { qedge[++qcnt].to = v; qedge[qcnt].next = qhead[u]; qhead[u] = qcnt; } int getfa(int x) { return x == par[x] ? x : par[x] = getfa(par[x]); } void dfs(int u) { par[u] = u; vis[u] = 1; for (int i = head[u]; i; i = edge[i].next) { int v = edge[i].to; if (!vis[v]) { dep[v] = dep[u] + edge[i].c; dfs(v); par[v] = u; } } for (int i = qhead[u]; i; i = qedge[i].next) { int v = qedge[i].to; if (vis[v]) { lca[i] = getfa(v); if (i % 2) lca[i + 1] = lca[i]; else lca[i-1] = lca[i]; } } } int main() { n = read(), m = read(); for (int i = 0; i < n - 1; i++) { int u = read(), v =read(), c = read(); addedge(u, v, c); addedge(v, u, c); } for (int i = 1; i <= m; i++) { int u = read(), v = read(); addqedge(u, v), addqedge(v, u); } dfs(1); ll ans = 0; int cnt = 0; for (int i = 1; i <= m; i++) { if (lca[2 * i] == qedge[2 * i].to) { cnt++; ans += dep[qedge[2*i].to] + dep[qedge[2*i-1].to] - 2 * dep[lca[2*i]]; } } printf("%d\n%lld\n", cnt, ans); return 0; }