comefrom: <awangdev>689. Maximum Sum of 3 Non-Overlapping Subarrays_1.java
code: private int[] calcLeft(int[] nums, int[] presum, int k) {
  
          int n = nums.length;
          int[] left = new int[n];
          for (int i = k, total = presum[k] - presum[0]; i < n; i++) {
              int sum = presum[i + 1] - presum[i + 1 - k]; 
              if (sum > total) {
                  left[i] = i + 1 - k;
                  total = sum;
              } else left[i] = left[i - 1];
          }
          
          return left;
      }
masked: private int [ ] sample_funcname ( int [ ] var_0 , int [ ] var_1 , int var_2 ) {
    int var_3 = var_0 . length ;
    int [ ] var_4 = new int [ var_3 ] ;
    for ( int var_5 = var_2 , var_6 = var_1 [ var_2 ] - var_1 [ 0 ] ;
    var_5 < var_3 ;
    var_5 ++ ) {
      int var_7 = var_1 [ var_5 + 1 ] - var_1 [ var_5 + 1 - var_2 ] ;
      if ( var_7 > var_6 ) {
        var_4 [ var_5 ] = var_5 + 1 - var_2 ;
        var_6 = var_7 ;
      }
      else var_4 [ var_5 ] = var_4 [ var_5 - 1 ] ;
    }
    return var_4 ;
  }
  