Problem Description
P1196 [NOI2002]银河英雄传说
Analysis of ideas
Accepted code
#pragma GCC optimize(2)
#include <bits/stdc++.h>
using namespace std;
#define mem(a,b) memset(a,b,sizeof(a))
#define pii pair<int,int>
#define gcd __gcd
const int inf = 0x3f3f3f3f;
const int maxn = 31110;
const int M = 1e9+7;
int n,m,k,ok;
int pre[maxn];
int d[maxn];
int num[maxn]; //表示第i列的飞船数量
int find(int x)
{
if(x == pre[x]) return x;
int k = find(pre[x]); //k记录祖先
d[x] += d[pre[x]]; //x的权值加上父亲的权值
return pre[x] = k;
}
signed main()
{
#ifdef ONLINE_JUDGE
#else
freopen("data.in", "r", stdin);
#endif
int T,a,b;
cin>>T;
char ch;
for(int i = 1; i < maxn; i++)
{
pre[i] = i;
num[i] = 1;
}
while(T--)
{
cin>>ch>>a>>b;
int x = find(a);
int y = find(b);
if(ch == 'M')
{
d[x] += num[y]; //x接y的后面
pre[x] = y;
num[y] += num[x];
num[x] = 0;
}
else
{
if(x == y)
{
cout<<abs(d[a]-d[b])-1<<endl;
}
else
{
cout<<-1<<endl;
}
}
}
return 0;
}