My issue
Problem Link: CS2023_404 Problem - CodeChef
wrong answer on submission of this code
#include <bits/stdc++.h>
using namespace std;
#define MOD 1000000007
long int power(int a,int b){
long int ans=1;
while(b>0){
a%=MOD;
if(b&1==1){
ans*=a;
ans%=MOD;
b–;
}
a*=a;
b=b>>1;
}
return ans%MOD;
}
int main(){
int t;
cin>>t;
while(t–){
int n;
cin>>n;
string s;
cin>>s;
int l1=0,l2=0,l3=0;
int r1=0,r2=0,r3=0;
for(int i=0;i<n;i++){
l1+=(s[i]==‘4’);
l2+=(s[i]==‘0’);
l3+=(s[i]==‘‘);
}
long long int ans=0;
for(int i=0;i<n;i++){
l1-=(s[i]==‘4’);
l3-=(s[i]==’’);
if(s[i]==‘0’ || s[i]==‘'){
int num=l1r1;
num*=power(2,l3+r3)%MOD;
ans+=num;
ans%+MOD;
num=(r3l1)%MOD;
num=power(2,l3+r3-1);
ans+=num;
ans%=MOD;
num=(r1l3)%MOD;
num=power(2,l3+r3-1);
ans+=num;
ans%=MOD;
num=(r3l3)%MOD;
num=power(2,l3+r3-2);
ans+=num;
ans%=MOD;
}
r1+=(s[i]==‘4’);
r3+=(s[i]==’*');
}
cout<<ans%MOD<<endl;
}
return 0;
}