// Zorah Fung, CSE143
// Demonstrates an exhaustive search algorithm by generating all permutations of 
// a given string.
public class Permutations {
   public static void main(String[] args) {
      permute("team");
   }

   // Outputs all permutations of the given string, one per line.
   // For example, TEAM can be permuted into MEAT, META, TMEA, ...
   public static void permute(String s) {
      permute(s, "");
   }

   private static void permute(String s, String soFar) {
      if (s.length() == 0) {
         System.out.println(soFar);
      } else {
         for (int i = 0; i < s.length(); i++) {
            // when we use primitive types or Strings, we can choose and
            // unchoose simply by passing a copy of the value to recursive
            // calls.
            char chosen = s.charAt(i);
            String remaining = s.substring(0, i) + s.substring(i + 1);
            // soFar = soFar + chosen; // explicit "choose"

            permute(remaining, soFar + chosen);

            // explicit unchoose if we modify soFar and s:
            // soFar = soFar.substring(0, soFar.length() - 1);
            // s = s.substring(0, i) + chosen + s.substring(i);
         }
      }
   }
}