Codeforces Round #210 (Div. 2) A. Levko and Table

让对角线的元素为k就行

#include <iostream>
using namespace std;

int main() {
    int n,k;
    cin >> n >> k;
    for(int i = 0 ; i < n; ++ i){
        for(int j = 0 ;  j < n ; ++ j){
            if(j != 0) cout<<" ";
            if( i == j) cout<<k;
            else cout<<0;
        }
        cout<<endl;
    }
    return 0;
}