硬币翻转

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <climits>
#include <cstring>
#include <string>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <vector>
#include <list>
#define rep(i,m,n) for(i=m;i<=n;i++)
#define rsp(it,s) for(set<int>::iterator it=s.begin();it!=s.end();it++)
#define mod 1000000007
#define inf 0x3f3f3f3f
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define ll long long
#define pi acos(-1.0)
const int maxn=1e6+10;
const int dis[4][2]={{0,1},{-1,0},{0,-1},{1,0}};
using namespace std;
ll gcd(ll p,ll q){return q==0?p:gcd(q,p%q);}
ll qpow(ll p,ll q,ll mo){ll f=1;while(q){if(q&1)f=f*p%mo;p=p*p%mo;q>>=1;}return f;}
int n,m,k,t;
string ans;
int main()
{
    int i,j;
    scanf("%d",&n);
    printf("%d\n",n);
    for(i=0;i<n;i++)ans+=‘0‘;
    for(i=0;i<n;i++)
    {
        for(j=0;j<n;j++)
        {
            if(i==j)continue;
            else
            {
                ans[j]=(ans[j]==‘0‘?‘1‘:‘0‘);
            }
        }
        cout<<ans<<endl;
    }
    //system ("pause");
    return 0;
}