1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204

#include <cstdio>
#include <vector>
#include <cctype>
#define lson (nown<<1)
#define rson (nown<<1|1)
#define mid ((l+r)>>1)
using namespace std;

//快读模版
namespace fast_io {
    inline char read() {...}
    inline void read(int &x) {...}
    inline void read(char *a){...}
    const int OUT_LEN = 1000000;
    char obuf[OUT_LEN], *ooh = obuf;
    inline void print(char c) {...}
    inline void print(int x) {...}
    inline void print(char *a){...}
    inline void flush() {...}
}using namespace fast_io;

const int MAXN = 110000;

int n,m;
int son[MAXN],top[MAXN],fa[MAXN],siz[MAXN],dep[MAXN];
int id[MAXN],id_to[MAXN],num[MAXN],cnt = 1;

vector<int> edge[MAXN];

//线段树节点定义
struct node{
    int num,lcol,rcol;
    bool lazy;
    node(int n = 0,int l = 0,int r = 0):num(n),lcol(l),rcol(r){};
    bool empty(){
        return num == 0;
    }
}pool[MAXN<<2];

//线段树节点的合并
inline node merge(node l,node r){
    //特判！！！
    if(l.empty()) return r;
    if(r.empty()) return l;
    node ans;
    ans.num = l.num+r.num;
    if(l.rcol == r.lcol) ans.num-=1;
    ans.lcol = l.lcol,ans.rcol = r.rcol;
    return ans;
}

//线段树的标记下传
inline void push_down(int nown,int l,int r){
    if(pool[nown].lazy){
        int c = pool[nown].lcol;
        pool[lson] = node(1,c,c),pool[lson].lazy = 1;
        pool[rson] = node(1,c,c),pool[rson].lazy = 1;
        pool[nown].lazy = 0;
    }
}

//反转区间
inline node reverse(node nown){
    swap(nown.lcol,nown.rcol);
    return nown;
}

//建树
inline void build(int nown,int l,int r){
    pool[nown].lazy = 0;
    if(l == r)
        pool[nown] = node(1,num[id_to[l]],num[id_to[l]]);
    else{
        build(lson,l,mid);
        build(rson,mid+1,r);
        pool[nown] = merge(pool[lson],pool[rson]);
    }
}

//线段树区间更新
inline void update(int nown,int l,int r,int ql,int qr,int c){
    if(ql<=l&&r<=qr){
        pool[nown] = node(1,c,c);
        pool[nown].lazy = 1;
    }
    else{
        push_down(nown,l,r);
        if(ql<=mid) update(lson,l,mid,ql,qr,c);
        if(qr>=mid+1) update(rson,mid+1,r,ql,qr,c);
        pool[nown] = merge(pool[lson],pool[rson]);
    }
}

//线段树区间查询颜色块树
inline node query(int nown,int l,int r,int ql,int qr){
    if(ql<=l&&r<=qr)
        return pool[nown];//这里的返回值是整个结构体
    else{
        push_down(nown,l,r);
        if(ql<=mid && mid+1<=qr){
            node ls,rs;
            ls = query(lson,l,mid,ql,qr);
            rs = query(rson,mid+1,r,ql,qr);
            return merge(ls,rs);
        }
        else if(qr<=mid)
            return query(lson,l,mid,ql,qr);
        else if(ql>=mid+1)
            return query(rson,mid+1,r,ql,qr);
    }
}

/*--- 以下为树链剖分模版 ---*/
inline void dfs1(int nown,int f,int depth){
    dep[nown] = depth,fa[nown] = f,siz[nown] = 1;
    son[nown] = 0;int maxsum = -1;
    for(int i = 0;i<edge[nown].size();i++){
        int to = edge[nown][i];
        if(to == f) continue;
        dfs1(to,nown,depth+1);
        siz[nown]+=siz[to];
        if(siz[to]>maxsum) maxsum = siz[to],son[nown] = to;
    }
}

inline void dfs2(int nown,int topf){
    top[nown] = topf,id[nown] = cnt,id_to[cnt] = nown;cnt++;
    if(!son[nown]) return;
    dfs2(son[nown],topf);
    for(int i = 0;i<edge[nown].size();i++){
        int to = edge[nown][i];
        if(to == fa[nown]||to == son[nown]) continue;
        dfs2(to,to);
    }
}

void update_range(int x,int y,int c){
    while(top[x]!=top[y]){
        if(dep[top[x]]<dep[top[y]]) swap(x,y);
        update(1,1,n,id[top[x]],id[x],c);
        x = fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y);
    update(1,1,n,id[x],id[y],c);
}

//这里多用了几个if else 和reverse来让颜色块接对方向
//可以同时交换lans和rans等来完成这一项(未经验证)
int query_range(int x,int y){
    node lans = node(0,0,0),rans = node(0,0,0);
    while(top[x]!=top[y]){
        if(dep[top[x]] > dep[top[y]]){
            lans = merge(lans,reverse(query(1,1,n,id[top[x]],id[x])));
            x = fa[top[x]];
        }
        else{
            rans = merge(query(1,1,n,id[top[y]],id[y]),rans);
            y = fa[top[y]];
        }
    }
    if(dep[x]<dep[y])
        lans = merge(lans,query(1,1,n,id[x],id[y]));
    else
        rans = merge(reverse(query(1,1,n,id[y],id[x])),rans);
    return merge(lans,rans).num;
}
/*--- 以上为树链剖分模版 ---*/

//程序的初始化
inline void init(){
    read(n),read(m);
    for(int i = 1;i<=n;i++)
        read(num[i]);
    int a,b;
    for(int i = 1;i<=n-1;i++){
        read(a),read(b);
        edge[a].push_back(b);
        edge[b].push_back(a);
    }
    dfs1(1,0,1);
    dfs2(1,1);
    build(1,1,n);
}

//回应询问
void solve(){
    char op[20];int a,b,c;
    for(int i = 1;i<=m;i++){
        read(op),read(a),read(b);
        if(op[0] == 'C')
            read(c),update_range(a,b,c);
        else if(op[0] == 'Q')
            print(query_range(a,b)),print('\n');
    }
}


int main(){
    init();
    solve();
    flush();
    return 0;
}