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
", 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;
}