int f(int i,int j,vector<vector<int>>&dp,string &s) {
    if(i>j) return 0;
    if(dp[i][j]!=-1) return dp[i][j];
int ways=0;
int count=0;
for(int ind=i;ind<min(i+2,j);ind++) {
   if(ind==i) {
       if(s[i]=='0') continue;
   }
   if(ind==i+1) {
       int no = (s[i]-'0')*10+(s[i]-'0');
       if(no>26) continue;
       if(no<10) continue;
       if(s[i]=='0') continue;
   }
    ways += 1 + f(ind+1,j,dp,s);
    count+=1;
}
if(count==0) {
    return 0;
    exit(0);
}

    return dp[i][j]=ways;
}


int Solution::numDecodings(string A) {
    //j = A.length()
    vector<vector<int>> dp(A.length()+1,vector<int>(A.length()+1,-1));
    int ans=f(0,A.length(),dp,A);
    if(ans<0) return 0;
    return ans;
}