lupgu P3950 部落冲突

题目链接

luogu P3950 部落冲突

题解

树剖线段树可以
lct还行

代码

#include<cstdio> 
#include<algorithm> 

inline int read() { 
    int x = 0,f = 1; 
    char c = getchar(); 
    while(c < '0' || c > '9')c = getchar(); 
    while(c <= '9' && c >= '0') x = x * 10 + c - '0',c = getchar(); 
    return x * f; 
} 
const int maxn = 300007; 
int ch[maxn][2],rev[maxn],fa[maxn]; 
bool isroot(int x) { return ch[fa[x]][1] != x && ch[fa[x]][0] != x;} 
void pushdown(int x) {
    if(rev[x]) {rev[x] ^= 1,std::swap(ch[x][1],ch[x][0]),rev[ch[x][1]] ^= 1,rev[ch[x][0]] ^= 1;}
} 
void rotate(int x) { 
    int y = fa[x],z = fa[y],d = (ch[y][1] == x) ^ 1; 
    if(!isroot(y)) ch[z][ch[z][1] == y] = x; 
    fa[x] = z; 
    ch[y][d ^ 1] = ch[x][d]; fa[ch[x][d]] = y; 
    ch[x][d] = y; fa[y] = x; 
} 
int stack[maxn],top = 0; 
void splay(int x) { 
    stack[++ top] = x; 
    for(int i = x;!isroot(i);i = fa[i]) stack[++ top] = fa[i]; 
    while(top) pushdown( stack[top --]); 
    while(!isroot(x)) {
        int y = fa[x],z = fa[y]; 
        if(!isroot(y)) { 
            if((ch[y][1] == x) ^ (ch[z][1] == y)) rotate(x); 
            else rotate(y); 
        } rotate(x); 
    } 
} 
void access(int x) {
    for(int i = 0;x;i = x , x = fa[x]) 
        splay(x), ch[x][1] = i; 
} 
void makeroot(int x) {access(x),splay(x),rev[x] ^= 1; }
void link(int x,int y) { makeroot(x),fa[x] = y;return splay(x); } 
void cut(int x,int y) {makeroot(x),access(y),splay(y),ch[y][0] = fa[x] = 0;}
int find(int x) { 
    for(access(x),splay(x);ch[x][0];x = ch[x][0]) ; 
        return x; 
} 
int p1[maxn],p2[maxn],num = 0; 
int main() { 
    int n,m; 
    n = read(),m = read(); 
    for(int a,b,i = 1;i < n;++ i) a = read(),b = read(),link(a,b); 
    char s[10]; 
    while(m -- ) { 
        int a,b; 
        scanf("%s",s + 1); 
        if(s[1] == 'U') {a = read(), link(p1[a],p2[a]);} 
        else if(s[1] == 'C') {a = read(),b = read();++ num,cut(p1[num] = a,p2[num] = b);} 
        else {a = read(),b = read();puts(find(a) == find(b) ? "Yes" : "No"); } 
    } 
    return 0; 
}