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 && s[ind]=='0' )||(ind==i+1 && s[ind-1]=='0')) continue;
    if(ind==i+1&&( (s[ind-1]-'0')*10+(s[ind]-'0')>26)) 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;
}