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题意
n条链,可以将一条链连到另一条链的尾部,查询两个点之间的距离
题解
带权并查集(几乎是模板吧)
调试记录
getf的时候,要先把f[x]的dis更新
#include <cstdio>
#define maxn 30005
using namespace std;
int _abs(int x){return x > 0 ? x : -x;}
int f[maxn], dis[maxn], size[maxn];
int getf(int x){
if (f[x] == x) return x;
getf(f[x]);
dis[x] += dis[f[x]];
return f[x] = getf(f[x]);
}
void Union(int x, int y){
int ux = getf(x), uy = getf(y);
dis[ux] += size[uy];
size[uy] += size[ux];
size[ux] = 0;
f[ux] = uy;
}
int T, n = 30000;
int main(){
scanf("%d", &T);
for (int i = 1; i <= n; i++) f[i] = i, dis[i] = 0, size[i] = 1;
while (T--){
char opt[5]; int x, y;
scanf("%s%d%d", opt, &x, &y);
if (opt[0] == 'M') Union(x, y);
if (opt[0] == 'C'){
if (getf(x) != getf(y)) puts("-1");
else printf("%d\n", _abs(dis[x] - dis[y]) - 1);
}
}
return 0;
}