C++ | Beats 100%
Code

# Code
```cpp []
class Solution {
public:
    #define ll long long int
    ll mod=1000000007;
    ll pow(int x,int p)
    {
        if(p==0)
           return 1;
        if(p==1)
           return x;
        ll half=pow(x,p/2);
        ll currPow=(half*half)%mod;
        if(p%2)
           currPow=(currPow*x)%mod;
        return currPow;     
    }
    int stringCount(int n) 
    {
        
        ll total=pow(26,n);
        ll noL=pow(25,n);  // noL=noE=noT  Use 3 times
        ll oneE=(n*pow(25,n-1))%mod;
        ll noLE=pow(24,n);  //noLE=noLT=noET Use 3 times
        ll noLET=pow(23,n);
        ll oneENoL=(n*pow(24,n-1))%mod; // oneENoL=oneENoT Use twice
        ll oneENoLT=(n*pow(23,n-1))%mod;
        ll res=(total
               - 3*noL%mod -oneE + 3*noLE%mod - noLET +2*oneENoL%mod -oneENoLT)%mod;
        return (res+mod)%mod;
    }
};
```
['C++']