HDU 5893 List wants to travel（树链剖分+线段树）

#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b)    for (int i(a); i <= (b); ++i)
#define dec(i, a, b)    for (int i(a); i >= (b); --i)
#define lson        i << 1, L, mid
#define rson        i << 1 | 1, mid + 1, R
#define MP        make_pair
#define fi        first
#define se        second

typedef long long LL;
typedef pair<int, int> PII;

const int N = 5e4 + 10;
const int A = 19;

vector <PII> v[N];
int father[N], deep[N], c[N], sz[N], son[N], f[N], top[N];
int lazy[N << 2], s[N << 2], lc[N << 2], rc[N << 2];
int st[N][A];
int n, m, tot;
char op[10];

void dfs(int x, int fa, int dep, int val){
	sz[x] = 1;
	father[x] = fa;
	deep[x] = deep[fa] + 1;
	c[x] = val;

	if (fa){ 
		st[x][0] = fa;
		for (int i = 0; st[st[x][i]][i]; ++i) st[x][i + 1] = st[st[x][i]][i];
	}

	for (auto cnt : v[x]){
		int u = cnt.fi, w = cnt.se;
		if (u == fa) continue;
		dfs(u, x, dep + 1, w);
		sz[x] += sz[u];
		if (sz[son[x]] < sz[u]) son[x] = u;
	}
}

void dfs2(int x, int tp){
	f[x] = ++tot;
	top[x] = tp;
	if (son[x]) dfs2(son[x], tp);

	for (auto cnt : v[x]){
		int u = cnt.fi, w = cnt.se;
		if (u == father[x] || u == son[x]) continue;
		dfs2(u, u);
	}
}

int LCA(int x, int y){
	for (; top[x] ^ top[y]; ){
		if (deep[top[x]] < deep[top[y]]) swap(x, y);
		x = father[top[x]];
	}

	return deep[x] > deep[y] ? y : x;
}

inline int updis(int x, int dis){
	dec(i, 17, 0) if ((1 << i) & dis) x = st[x][i], dis ^= (1 << i);
	return x;
}

inline void pushup(int i){
	lc[i] = lc[i << 1];
	rc[i] = rc[i << 1 | 1];
	if (rc[i << 1] ^ lc[i << 1 | 1]) s[i] = s[i << 1] + s[i << 1 | 1];
	else s[i] = s[i << 1] + s[i << 1 | 1] - 1;
}

inline void pushdown(int i, int L, int R){
	int tmp = lazy[i];
	if (tmp == -1 || L == R) return;

	s[i << 1]      = s[i << 1 | 1]    = 1;
	lazy[i << 1]   = lazy[i << 1 | 1] = tmp;

	lc[i << 1]     = rc[i << 1]       = tmp;
	lc[i << 1 | 1] = rc[i << 1 | 1]   = tmp;
	lazy[i] = -1;
}

void build(int i, int L, int R){
	s[i] = 1;
	lazy[i] = -1;

	if (L == R) return;
	int mid = (L + R) >> 1;

	build(lson);
	build(rson);
}

void change(int i, int L, int R, int l, int r, int val){
	pushdown(i, L, R);
	if (L == l && R == r){
		lc[i] = rc[i] = val;
		s[i]  = 1;
		lazy[i] = val;
		return;
	}

	int mid = (L + R) >> 1;
	if (r <= mid) change(lson, l, r, val);
	else if (l > mid) change(rson, l, r, val);
	else{
		change(lson, l, mid, val);
		change(rson, mid + 1, r, val);
	}

	pushup(i);
}

int query(int i, int L, int R, int l, int r){
	pushdown(i, L, R);
	if (L == l && R == r) return s[i];

	int mid = (L + R) >> 1;
	if (r <= mid) return query(lson, l, r);
	else if (l > mid) return query(rson, l, r);
	else{
		int tmp = 1;
		if (rc[i << 1] ^ lc[i << 1 | 1]) tmp = 0;
		return query(lson, l, mid) + query(rson, mid + 1, r) - tmp;
	}
}

int getcolor(int i, int L, int R, int x){
	pushdown(i, L, R);
	if (L == R) return lc[i];
	int mid = (L + R) >> 1;
	if (x <= mid) return getcolor(lson, x);
	else return getcolor(rson, x);
}

int solvesum(int x, int tp){
	int ret = 0;
	for (; top[x] ^ top[tp] ;){
		ret += query(1, 1, n, f[top[x]], f[x]);
		if (getcolor(1, 1, n, f[top[x]]) == getcolor(1, 1, n, f[father[top[x]]])) --ret;
		x = father[top[x]];
	}

	ret += query(1, 1, n, f[tp], f[x]);
	return ret;
}

void solvechange(int x, int tp, int val){
	for (; top[x] ^ top[tp]; ){
		change(1, 1, n, f[top[x]], f[x], val);
		x = father[top[x]];
	}

	change(1, 1, n, f[tp], f[x], val);
}

int main(){

	while (~scanf("%d%d", &n, &m)){
		tot = 0;
		rep(i, 0, n + 1) v[i].clear();
		memset(st, 0, sizeof st);
		memset(f, 0, sizeof f);
		memset(father, 0, sizeof father);
		rep(i, 2, n){
			int x, y, z;
			scanf("%d%d%d", &x, &y, &z);
			v[x].push_back(MP(y, z));
			v[y].push_back(MP(x, z));
		}

		memset(son, 0, sizeof son);
		dfs(1, 0, 1, 0);
		dfs2(1, 1);

		memset(lc, 0, sizeof lc);
		memset(rc, 0, sizeof rc);
		build(1, 1, n);
		rep(i, 2, n) change(1, 1, n, f[i], f[i], c[i]);
		while (m--){
			scanf("%s", op);
			if (op[0] == ‘Q‘){
				int x, y;
				scanf("%d%d", &x, &y);
				if (x == y){
					puts("0");
					continue;
				}

				if (deep[x] < deep[y]) swap(x, y);
				int t = LCA(x, y);
				if (y == t){
					int yy = updis(x, deep[x] - deep[y] - 1);
					printf("%d\n", solvesum(x, yy));
					continue;
				}

				int xx = updis(x, deep[x] - deep[t] - 1);
				int yy = updis(y, deep[y] - deep[t] - 1);
				int reta = solvesum(x, xx);
				int retb = solvesum(y, yy);
				int ret;
				if (getcolor(1, 1, n, f[xx]) == getcolor(1, 1, n, f[yy]))
					ret = reta + retb - 1;
				else
					ret = reta + retb;
				printf("%d\n", ret);
			}

			else{
				int x, y, z;
				scanf("%d%d%d", &x, &y, &z);
				if (x == y) continue;

				if (deep[x] < deep[y]) swap(x, y);
				int t = LCA(x, y);
				if (y == t){
					int yy = updis(x, deep[x] - deep[y] - 1);
					solvechange(x, yy, z);
					continue;
				}

				int xx = updis(x, deep[x] - deep[t] - 1);
				int yy = updis(y, deep[y] - deep[t] - 1);

				solvechange(x, xx, z);
				solvechange(y, yy, z);            

			}
		}
	}

	return 0;
}