FZU 2082 过路费

题目链接

树链抛分改动边的模板题

代码：

#include <cstdio>
#include <cstring>
#include <vector>
using namespace std;

typedef long long ll;
const int N = 50005;

int dep[N], id[N], sz[N], top[N], son[N], fa[N], idx;
int n, m;
ll bit[N];

struct Edge {
	int u, v;
	ll val;
	void read() {
		scanf("%d%d%lld", &u, &v, &val);
	}
} e[N];

vector<int> g[N];

inline int lowbit(int x) {
	return x&(-x);
}

void dfs1(int u, int f, int d) {
	dep[u] = d;
	sz[u] = 1;
	fa[u] = f;
	son[u] = 0;
	for (int i = 0; i < g[u].size(); i++) {
		int v = g[u][i];
		if (v == f) continue;
		dfs1(v, u, d + 1);
		sz[u] += sz[v];
		if (sz[son[u]] < sz[v])
			son[u] = v;
	}
}

void dfs2(int u, int tp) {
	top[u] = tp;
	id[u] = idx++;
	if (son[u]) dfs2(son[u], tp);
	for (int i = 0; i < g[u].size(); i++) {
		int v = g[u][i];
		if (v == fa[u] || v == son[u]) continue;
		dfs2(v, v);
	}
}

void add(int x, ll v) {
	while (x < N) {
		bit[x] += v;
		x += lowbit(x);
	}
}

ll query(int x) {
	ll ans = 0;
	while (x) {
		ans += bit[x];
		x -= lowbit(x);
	}
	return ans;
}

ll query(int l, int r) {
	return query(r) - query(l - 1);
}

ll gao(int u, int v) {
	int tp1 = top[u], tp2 = top[v];
	ll ans = 0;
	while (tp1 != tp2) {
		if (dep[tp1] < dep[tp2]) {
			swap(tp1, tp2);
			swap(u, v);
		}
		ans += query(id[tp1], id[u]);
		u = fa[tp1];
		tp1 = top[u];
	}
	if (u == v) return ans;
	if (dep[u] > dep[v]) swap(u, v);
	ans += query(id[son[u]], id[v]);
	return ans;
}

int main() {
	while (~scanf("%d%d", &n, &m)) {
		idx = 0;
		memset(bit, 0, sizeof(bit));
		for (int i = 1; i <= n; i++) g[i].clear();
		for (int i = 1; i < n; i++) {
			e[i].read();
			g[e[i].u].push_back(e[i].v);
			g[e[i].v].push_back(e[i].u);
		}
		dfs1(1, 0, 1);
		dfs2(1, 1);
		for (int i = 1; i < n; i++) {
			if (dep[e[i].u] < dep[e[i].v]) swap(e[i].u, e[i].v);
			add(id[e[i].u], e[i].val);
		}
		int ty, a, b;
		while (m--) {
			scanf("%d%d%d", &ty, &a, &b);
			if (ty == 0) {
				ll tmp = query(id[e[a].u], id[e[a].u]);
				add(id[e[a].u], (ll)b - tmp);
			} else printf("%lld\n", gao(a, b));
		}
	}
	return 0;
}