【BZOJ2243】【SDOI2011】染色 （LCT）

链接：http://www.lydsy.com/JudgeOnline/problem.php?id=2243

练了一发LCT，唔调了好久感觉是下传标记的问题可是不知道哪里错了。问了问老司机ljy，确实是出事了。。

唔大概就是 每一次flip的下传要注意一下两个儿子各自的lc和rc吧qwq

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#define MaxN 200010
using namespace std;
int n, m, top;
int ch[MaxN][2];
int Q[MaxN], sum[MaxN], val[MaxN], type[MaxN], flip[MaxN], p[MaxN], mark[MaxN], lc[MaxN], rc[MaxN];
//splay

bool isroot(int x){
    return ch[p[x]][0] != x && ch[p[x]][1] != x;
}

#define l ch[x][0]
#define r ch[x][1]

void push_up(int x){
    sum[x] = sum[l] + sum[r] + 1;
    if (l) sum[x] -= (rc[l] == val[x]), lc[x] = lc[l]; else lc[x] = val[x];
    if (r) sum[x] -= (lc[r] == val[x]), rc[x] = rc[r]; else rc[x] = val[x];
}

void updata(int x, int c){
    if (!x) return;
    sum[x] = mark[x] = 1; 
    lc[x] = rc[x] = val[x] = c;
}

void Flip(int x){
    flip[x] ^= 1; swap(lc[l], rc[l]); swap(rc[r], lc[r]);
}

#undef l
#undef r

void push_down(int x){
    int l = ch[x][0], r = ch[x][1];
    if (flip[x]){
        flip[x] = 0;
        Flip(l); Flip(r);        
        swap(ch[x][0], ch[x][1]);
    }
    if (mark[x]){
        mark[x] = 0;
        updata(l, val[x]); updata(r, val[x]); 
    }
}

void rotate(int x){
    int y = p[x], z = p[y];
    if (!isroot(y)) ch[z][ch[z][1] == y] = x;
    int l = ch[y][1] == x, r = l ^ 1;
    
    p[x] = z;
    p[y] = x;
    p[ch[x][r]] = y;
    
    ch[y][l] = ch[x][r];
    ch[x][r] = y;
    push_up(y); push_up(x);
}

void splay(int x){
    int top = 1;
    Q[top] = x;
    for (int t = x; !isroot(t); t = p[t]) Q[++top] = p[t];
    while (top) push_down(Q[top--]);
    while (!isroot(x)){
        int y = p[x], z = p[y];
        if (!isroot(y)){
            if ((ch[y][1] == x) ^ (ch[z][1] == y)) rotate(x);
            else rotate(y);
        }
        rotate(x);
    }
}

// lct

void Access(int x){
    for (int t = 0; x; t = x, x = p[x]) {
        splay(x); ch[x][1] = t; push_up(x);
    }
}

void Make_root(int x){
    Access(x); splay(x); flip[x] ^= 1;
}

void Link(int u, int v){
    Make_root(u); p[u] = v;
}

void Split(int u, int v){
    Make_root(v); Access(u); splay(u);
}

//
void Read_Data(){
    scanf("%d%d", &n, &m);
    int u, v;
    //val[0] = rc[0] = lc[0] = -1;
    for (int i = 1; i <= n; i++) scanf("%d", &val[i]), lc[i] = rc[i] = val[i];
//    for (int i = 1; i <= n; i++) sum[i] = 1; 
    for (int i = 1; i < n; i++) {    
        scanf("%d%d", &u, &v);
        Link(u, v); 
        
}

void Solve(){
    char s[5];
    int u, v, c;
    for (int i = 1; i <= m; i++) {
        scanf("%s%d%d", s, &u, &v);
        if (s[0] == 'Q') {
            Split(u, v); 
            printf("%d
", sum[u]);
        }
        else {
            scanf("%d", &c);
            Split(u, v); updata(u, c); 
        }    
    }
}

int main(){
    freopen("paint.in", "r", stdin);
    freopen("paint.out", "w", stdout);
    Read_Data();
    Solve();
    return 0;
}