leetcode

first-non-repeating.dart (816B)

---

 import 'dart:io';
 //This is a leetcode style question, but not from leetcode.
 //The idea is to find the first character of the input string that
 //does not repeat in the string. This is the optimized way using maps
 //which is linear time, but the simple solution would be brute force checking
 //every single charcter which would be O(n^2);
 void main(){
     stdout.write("Enter text to find the first non-repeating character: ");
     String s = stdin.readLineSync() ?? "N/A";
     Map<String,int> vals = {};
     for(int i = 0 ; i < s.length; ++i){
         vals[s[i]] = (vals[s[i]] ?? 0) + 1;
     }
     for(int i = 0 ; i < s.length ; ++i){
             if(vals[s[i]] == 1){
                 print(s[i] + " is the first character that does not repeat in the string.");
                 break;
             }
         }
     }