Poj3237Tree 树链剖分

点更新 ，段更新， 段查询。 注意的是 线段树维护区间最大值 ，在反转的时候 不能直接取反，那样就变成了 当时的最小值。

所以维护两个值，一个最小值 一个最大值 ，在进行反转操作的时候，取反并且交换两个值。

#include<iostream>

#include<cstdio>

#include<cstring>

#include<map>

#include<vector>

#include<stdlib.h>

using namespace std;

typedef long long LL;

const int maxn = 22222;

struct Node

{

    int next; int to;

}e[maxn * 2];

int edge[maxn][10];

#define lson l,mid,rt<<1

#define rson mid+1,r,rt<<1|1

int len; int z;

int size[maxn]; int son[maxn]; int deep[maxn], father[maxn];

int color[maxn << 2];

int sum[maxn << 2];

int head[maxn];

int pos[maxn]; int top[maxn];

const int INF = 1 << 30;

int sum1[maxn << 2];



void add(int from, int to)

{

    e[len].to = to;

    e[len].next = head[from];

    head[from] = len++;

}



void init(int x)

{

    size[x] = 1; son[x] = 0;

    for (int i = head[x]; i != -1; i = e[i].next){

        int cc = e[i].to;

        if (cc == father[x]) continue;

        father[cc] = x; deep[cc] = deep[x] + 1;

        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 build(int l, int r, int rt)

{

    sum[rt] = -INF; sum1[rt] = INF;

    color[rt] = 0;

    if (l == r) return;

    int mid = (l + r) >> 1;

    build(lson); build(rson);

}



void down(int rt)

{

    if (color[rt]){

        sum[rt << 1] = -sum[rt << 1]; sum[rt << 1 | 1] = -sum[rt << 1 | 1]; sum1[rt << 1] = -sum1[rt << 1]; sum1[rt << 1 | 1] = -sum1[rt << 1 | 1];

        swap(sum[rt << 1], sum1[rt << 1]); swap(sum[rt << 1 | 1], sum1[rt << 1 | 1]);

        color[rt << 1] ^= 1; color[rt << 1 | 1] ^= 1;

        color[rt] = 0;

    }

}



void up(int rt)

{

    sum[rt] = max(sum[rt << 1], sum[rt << 1 | 1]);

    sum1[rt] = min(sum1[rt << 1], sum1[rt << 1 | 1]);

}



void update(int L, int R, int l, int r, int rt)

{

    if (L <= l&&r <= R) {

        color[rt] ^= 1; sum[rt] = -sum[rt]; sum1[rt] = -sum1[rt]; swap(sum[rt], sum1[rt]);

        return;

    }

    int mid = (l + r) >> 1;

    down(rt);

    if (L <= mid) update(L, R, lson);

    if (R > mid) update(L, R, rson);

    up(rt);

}



void update1(int key, int ans, int l, int r, int rt)

{

    if (l == r){

        sum1[rt] = ans;

        sum[rt] = ans; return;

    }

    down(rt);

    int mid = (l + r) >> 1;

    if (key <= mid) update1(key, ans, lson);

    else update1(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];

    down(rt);

    int mid = (l + r) >> 1;

    int Max = -INF;

    if (L <= mid) Max = max(Max, ask(L, R, lson));

    if (R > mid) Max = max(Max, ask(L, R, rson));

    return Max;

}



int gao(int x, int y)

{

    int Max = -INF;

    int fx = top[x]; int fy = top[y];

    while (fx != fy){

        if (deep[fx] < deep[fy]){

            swap(x, y); swap(fx, fy);

        }

        Max = max(Max, ask(pos[fx], pos[x], 1, z, 1));

        x = father[fx]; fx = top[x];

    }

    if (x == y) return Max;

    if (deep[x]>deep[y])swap(x, y);

    Max = max(Max, ask(pos[son[x]], pos[y], 1, z, 1));

    return Max;



}



void gao1(int x, int y)

{

    int fx = top[x]; int fy = top[y];

    while (fx != fy){

        if (deep[fx]<deep[fy]) swap(x, y), swap(fx, fy);

        update(pos[fx], pos[x], 1, z, 1);

        x = father[fx];  fx = top[x];

    }

    if (x == y) return;

    if (deep[x]>deep[y]) swap(x, y);

    update(pos[son[x]], pos[y], 1, z, 1);

}





int main()

{

    // freopen("input.txt","r",stdin);

    //freopen("output.txt","w",stdout);

    int t;

    scanf("%d", &t);

    int n, a, b;

    char str[1000];

    while (t--){

        scanf("%d", &n);

        len = 0; z = 0;

        memset(head, -1, sizeof(head));

        deep[1] = 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); build(1, z, 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]);

            update1(pos[edge[i][1]], c, 1, z, 1);

        }

        while (scanf("%s", str) != EOF){

            if (str[0] == 'D') break;

            if (str[0] == 'Q'){

                scanf("%d%d", &a, &b);

                int t = gao(a, b);

                printf("%d\n", t);

            }

            if (str[0] == 'C'){

                scanf("%d%d", &a, &b);

                edge[a][2] = b;

                update1(pos[edge[a][1]], b, 1, z, 1);

            }

            if (str[0] == 'N'){

                scanf("%d%d", &a, &b);

                gao1(a, b);

            }

        }

    }

    return 0;

}