时间复杂度 O(n)
维护B数组中编号到下标的映射,找到同组循环的所有编号
#include <bits/stdc++.h>
using namespace std;
const int N = 110;
int a[N], b[N];
int main()
{
int n;
cin >> n;
unordered_map<int, int> m;
for(int i = 1; i <= n; i ++) cin >> a[i];
for(int i = 1; i <= n; i ++)
{
cin >> b[i];
m[b[i]] = i;
}
int cnt = 0, len = -1;
for(int i = 1; i <= n; i ++)
{
if( a[i] != 0 && a[i] != b[i] )
{
int cur = 1;
int ni = m[a[i]];
while(i != ni)
{
int &x = a[ni];
ni = m[a[ni]];
x = 0;
cur ++;
}
cnt ++;
len = max(len, cur);
}
}
cout << cnt << " " << len << endl;
return 0;
}