Obtain a Permutation 乱搞

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll mod=1e9+7;
const int N=1e6+100;

map<int,int>mp;

int main() {
    int n,m;
    cin>>n>>m;
    int a[2*n+1][m+1];
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
            scanf("%d",&a[i][j]),a[i+n][j]=a[i][j];
    int ans=0;

    for(int temp,j=1;j<=m;j++,ans+=temp) {
        temp=n;
        mp.clear();
        for(int i=1;i<=2*n;i++) a[i][j]-=(i-1)*m;
        for(int i=1;i<=n;i++) mp[a[i][j]]++;
        for(int i=1;i<=n;i++) {
            temp=min(temp,i-1+n-mp[j-(i-1)*m]);
            --mp[a[i][j]];
            ++mp[a[i+n][j]];
        }
    }
    cout<<ans;
}