comefrom: <gouthampradhan>array_MissingNumber_1.java
code: public int missingNumber(int[] nums) {
      int sum = 0;
      int n = nums.length;
      for (int num : nums) {
        sum += num;
      }
      int arrSum = (((n + 1)) * n) / 2;
      if (arrSum == sum) return 0;
      else return arrSum - sum;
    }
masked: public int sample_funcname ( int [ ] var_0 ) {
    int var_1 = 0 ;
    int var_2 = var_0 . length ;
    for ( int var_3 : var_0 ) {
      var_1 += var_3 ;
    }
    int var_4 = ( ( ( var_2 + 1 ) ) * var_2 ) / 2 ;
    if ( var_4 == var_1 ) return 0 ;
    else return var_4 - var_1 ;
  }
  