SDOI2011 染色

先知道是树剖后一下子就想出来了。。。。。。应该不难的，但是代码写得有点长，调了好久。。。。。。。

还要感谢段大神帮我调出来了^-^是query写错了，在fu == fv的时候，没有处理好标记ＱＡＱ

here is my program

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<vector>

using namespace std;

#define lc (o<<1)
#define rc (o<<1|1)
#define pb push_back
#define For(i, a, b) for(int i = (a); i <= (int)(b); i++)

#define MAXN (100000+5)

int n, ql, qr, dfsn, cp;
int rco[MAXN], fa[MAXN], siz[MAXN], top[MAXN], son[MAXN], dep[MAXN], w[MAXN], co[MAXN];
vector<int> G[MAXN];

struct node{
    int st, en, cnt;

    node(){
        st = en = cnt = 0;
    }

    node operator +(const node &rhs)const{
        if(!rhs.st && !rhs.en && !rhs.cnt) return *this;
        if(!st && !en && !cnt) return rhs;

        node ret;
        ret.cnt = cnt+rhs.cnt;
        if(en == rhs.st) ret.cnt--;
        ret.st = st; ret.en = rhs.en;
        return ret;
    }

    void print(){
        printf("%d %d %d\n", st, en, cnt);
    }
};

struct Seg_tree{
    node inf[MAXN*4]; 
    int bj[MAXN*4];

    inline void pushdown(int o){
        if(!bj[o]) return;    
        
        bj[o] = false; bj[lc] = bj[rc] = true;
        inf[lc].st = inf[rc].st = inf[lc].en = inf[rc].en = inf[o].st;
        inf[lc].cnt = inf[rc].cnt = inf[o].cnt;
    }

    inline void maintain(int o){
        inf[o] = inf[lc]+inf[rc];
    }

    inline void build(int o, int L, int R){
        if(L == R){
            ++cp;
            inf[o].st = inf[o].en = rco[cp]; inf[o].cnt = 1;
            return;
        }                                                                                                                                                                                                                                                                                                        

        int mid = (L+R)>>1;
        build(lc, L, mid); build(rc, mid+1, R);
        maintain(o);
    }

    inline void modify(int o, int L, int R, int col){
        if(ql <= L && qr >= R){
            inf[o].st = inf[o].en = col; inf[o].cnt = 1; bj[o] = true;
            return;
        }

        pushdown(o);
        int mid = (L+R)>>1;
        if(ql <= mid) modify(lc, L, mid, col);
        if(qr > mid) modify(rc, mid+1, R, col);
        maintain(o);
    }

    inline node query(int o, int L, int R){
        if(ql <= L && qr >= R) return inf[o];        
        
        pushdown(o);
        int mid = (L+R)>>1;

        if(qr <= mid) return query(lc, L, mid);
        else if(ql > mid) return query(rc, mid+1, R);
        else return query(lc, L, mid)+query(rc, mid+1, R);
    }
}ST;

void dfs1(int now, int La, int D){
    fa[now] = La; siz[now] = 1; dep[now] = D;
    
    int maxw = 0;
    For(i, 0, G[now].size()-1){
        int v = G[now][i];
        if(v == La) continue;

        dfs1(v, now, D+1);
        siz[now] += siz[v];
        if(siz[v] > maxw) maxw = siz[v], son[now] = v;
    }
}

void dfs2(int now, int Top){
    top[now] = Top; w[now] = ++dfsn;

    int v;
    if(son[now]) dfs2(son[now], Top);
    For(i, 0, G[now].size()-1){
        v = G[now][i];
        if(v == son[now] || v == fa[now]) continue;

        dfs2(v, v);
    }
}

void update(int u, int v, int col){
    while(u != v){
        int fu = top[u], fv = top[v];
        if(dep[fu] < dep[fv]){
            swap(u, v); swap(fu, fv);
        }

        if(fu == fv){
            ql = min(w[u], w[v]); qr = w[u]+w[v]-ql;
            ST.modify(1, 1, n, col);
            break;
        }

        ql = w[fu]; qr = w[u];
        ST.modify(1, 1, n, col);

        u = fa[fu];
    }

    if(u == v){
        ql = qr = w[u];
        ST.modify(1, 1, n, col);
    }
}

void query(int u, int v){
    node tu, tv;
    while(u != v){
        int fu = top[u], fv = top[v];
        if(dep[fu] < dep[fv]){
            swap(u, v); swap(fu, fv); swap(tu, tv);
        }
        if(fu == fv){
            ql = min(w[u], w[v]); qr = w[u]+w[v]-ql;
            if(ql == w[u]) tv = ST.query(1, 1, n)+tv;
            else tu = ST.query(1, 1, n)+tu;
            break;
        }

        ql = w[fu]; qr = w[u];
        tu = ST.query(1, 1, n)+tu;

        u = fa[fu];
    }
    if(u == v){
        ql = qr = w[u];
        tu = ST.query(1, 1, n)+tu;
    }
    
    int ans = tu.cnt+tv.cnt;
    if(tu.st == tv.st) ans--;
    printf("%d\n", ans);
}
 
int main(){
    int m;
    scanf("%d%d", &n, &m);
    For(i, 1, n) scanf("%d", &co[i]);
    For(i, 1, n-1){
        int x, y;
        scanf("%d%d", &x, &y);
        G[x].pb(y); G[y].pb(x);    
    } 
    
    dfs1(1, 0, 1); dfs2(1, 1);
    For(i, 1, n) rco[w[i]] = co[i];

    ST.build(1, 1, n);

    char s[5];
    int a, b, c;
    while(m--){
        scanf("%s", s);

        if(s[0] == 'C'){
            scanf("%d%d%d", &a, &b, &c);
               update(a, b, c); 
        }else{
            scanf("%d%d", &a, &b);
            if(a != b) query(a, b);
            else printf("1\n");
        }
    }
        
    return 0;
}