comefrom: <awangdev>287. Find the Duplicate Number_1.java
code: public int findDuplicate(int[] nums) {
          int slow = nums[0], fast = nums[nums[0]]; 
          while (slow != fast) {
              slow = nums[slow];
              fast = nums[nums[fast]];
          }
          int finder = 0;
          while (slow != finder) {
              slow = nums[slow];
              finder = nums[finder];
          }
          return slow;
      }
masked: public int sample_funcname ( int [ ] var_0 ) {
    int var_1 = var_0 [ 0 ] , var_2 = var_0 [ var_0 [ 0 ] ] ;
    while ( var_1 != var_2 ) {
      var_1 = var_0 [ var_1 ] ;
      var_2 = var_0 [ var_0 [ var_2 ] ] ;
    }
    int var_3 = 0 ;
    while ( var_1 != var_3 ) {
      var_1 = var_0 [ var_1 ] ;
      var_3 = var_0 [ var_3 ] ;
    }
    return var_1 ;
  }
  