Poj2763Housewife Wind树链剖分

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#include<iostream>
#include<cstdio>
#include<cstring>
#include<map>
#include<vector>
#include<stdlib.h>
using namespace std;
typedef long long LL;
const int maxn = 222222;

struct Node
{
    int to;int next;
}e[maxn*2];
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1

int head[maxn];
int son[maxn];
int top[maxn];
int father[maxn];
int deep[maxn];
int len;int z;
int size[maxn];
int pos[maxn];
int sum[maxn<<2];
void add(int from, int to)
{
    e[len].to = to;
    e[len].next = head[from];
    head[from] = len++;
}
int edge[maxn][10];

void init(int x)
{
    son[x] = 0; size[x] = 1;
    for (int i = head[x]; i != -1; i = e[i].next){
        int cc = e[i].to;
        if (cc == father[x]) continue;
        deep[cc] = deep[x] + 1; father[cc] = x;
        init(cc);
        size[x] += size[cc];
        if (size[son[x]] < size[cc]) son[x] = cc;
    }
}

void dfs(int x, int tp)
{
    pos[x] = ++z;top[x] = tp;
    if (son[x]) dfs(son[x], tp);
    for (int i = head[x]; i != -1; i = e[i].next){
        int cc = e[i].to;
        if (cc == father[x] || cc == son[x]) continue;
        dfs(cc, cc);
    }
}

void up(int rt)
{
    sum[rt] = sum[rt << 1] + sum[rt << 1 | 1];
}

void update(int key, int ans, int l, int r, int rt)
{
    if (l == r){
        sum[rt] = ans; return;
    }
    int mid = (l + r) >> 1;
    if (key <= mid) update(key, ans, lson);
    else update(key, ans, rson);
    up(rt);
}

int ask(int L, int R, int l, int r, int rt)
{
    if (L <= l&&r <= R) return sum[rt];
    int mid = (l + r) >> 1;
    int ans = 0;
    if (L <= mid) ans += ask(L, R, lson);
    if (R > mid) ans += ask(L, R, rson);
    return ans;
}

int gao(int x, int y)
{
    int ans = 0;
    int fx = top[x]; int fy = top[y];
    while (fx != fy){
        if (deep[fx] < deep[fy]){
            swap(fx, fy); swap(x, y);
        }
        ans += ask(pos[fx], pos[x], 1, z, 1);
        x = father[fx]; fx = top[x];
    }
    if (x == y) return ans;
    if (deep[x]>deep[y]) swap(x, y);
    ans += ask(pos[x] + 1, pos[y], 1, z, 1);
    return ans;
}

int main()
{
    int n,q,s;
    int a,b,c;
    while (cin >> n >> q >> s){
        memset(sum,0,sizeof(sum));
        len = 0;z =0;
        memset(head,-1,sizeof(head));
        deep[s]=1 ;
        for (int i = 1; i < n ; i++){
            scanf("%d%d%d", &edge[i][0], &edge[i][1], &edge[i][2]);
            add(edge[i][0], edge[i][1]); add(edge[i][1], edge[i][0]);
        }
        init(1); dfs(1, 1);
        for (int i = 1; i < n ; i++){
            int a = edge[i][0]; int b = edge[i][1]; int c = edge[i][2];
            if (deep[a]>deep[b]) swap(edge[i][0], edge[i][1]);
            update(pos[edge[i][1]], c, 1, z, 1);
        }
        while (q--){
            scanf("%d", &a);
            if (a == 0){
                scanf("%d", &b);
                int t = gao(b, s);
                cout << t << endl;
                s = b;
            }
            else {
                scanf("%d%d", &b, &c);
                edge[b][2] = c;
                update(pos[edge[b][1]], c, 1, z, 1);
            }
        }
    }
    return 0;
}