985B - Switches and Lamps - CodeForces Solution

/*
 * @author islam Mohamed Abououf
 */

#include "bits/stdc++.h"
using namespace std ;
#define ll long long
#define cin(v) for(auto &el : (v)) cin >> el
#define cout(v) for(auto &el : (v)) cout << el << ' ' ; cout << nl ;
#define Tc int t ; cin>>t ;while(t--)
#define all(vc) vc.begin() , (vc).end()
#define vi vector<int>
#define vii vector<pair<int , int>>
#define vvi vector<vector<int>>
#define mpii map<int,int>
#define mpll map<ll,ll>
#define vll  vector<ll>
#define nl '\n'
#define yes cout << "YES" << nl ;
#define no cout << "NO" << nl ;
#define _ ios::sync_with_stdio(false);cout.tie(NULL);cin.tie(NULL);


ll mod = 1e9+7;
int OO = 1e9;
ll N = 2e5+5 ;
vector<bool> isPrime(N,true);
set<ll> primes;
vi freq(N) ;

int get_divisors(ll num){
    set<ll> st ;
    for (ll i = 2; i*i <= num; ++i) {
        if(num%i == 0){
            st.insert(i) ;
            st.insert(num/i);
        }
    }
    return (int) st.size();
}
void sieve(){
    isPrime[0]= false ;
    isPrime[1]= false ;
    for (int i = 2; i <N ; ++i) {
        if(isPrime[i]){
            primes.insert(i) ;
            for (int j = i+i; j<N ; j+=i) {
                isPrime[j]= false ;
            }
        }
    }
}
ll gcd(ll a, ll b){
    if(b==0) return a;
    return gcd(b, a%b);
}
ll fact(ll a){
    if(a==1)
        return a ;
    return a * fact(a-1) ;
}
ll lcm(ll a, ll b){
    return a/gcd(a,b)*b;
}
vector<string> switches ;
ll n,m;
vector<bool> dep(2005 , true) ;
void validate(){
    for (int i = 0; i <m; ++i) {
        int sum =0 , x = 0;
        for (int j = 0; j < n; ++j) {
            if(switches[j][i]=='1'){
                sum++ ;
                x = j ;
            }
        }
        if(sum==1) dep[x] = false;
    }
}
// 1 1
// 2 1
// 4 -1
// 5 1

void answer() {
    cin >> n>>m;
    for (int i = 0; i < n; ++i) {
        string x;
        cin >> x;
        switches.push_back(x);
    }
    validate() ;
    for (int i = 0; i < n; ++i) {
        if(dep[i]) {
            yes return;
        }
    }
    no
}

int main() {
    _
//    Tc{
//        answer() ;
//    }
    answer();

}