comefrom: <awangdev>70. Climbing Stairs_2.java
code: public int climbStairs(int n) {
          if (n <= 1) {
              return 1;
          }
          int[] dp = new int[2];
          dp[0] = 1;
          dp[1] = 1;
          for (int i = 2; i <= n; i++) {
              dp[i % 2] = dp[(i - 1) % 2] + dp[(i - 2) % 2];
          }
          
          return dp[n % 2];
      }
masked: public int sample_funcname ( int var_0 ) {
    if ( var_0 <= 1 ) {
      return 1 ;
    }
    int [ ] var_3 = new int [ 2 ] ;
    var_3 [ 0 ] = 1 ;
    var_3 [ 1 ] = 1 ;
    for ( int var_5 = 2 ;
    var_5 <= var_0 ;
    var_5 ++ ) {
      var_3 [ var_5 % 2 ] = var_3 [ ( var_5 - 1 ) % 2 ] + var_3 [ ( var_5 - 2 ) % 2 ] ;
    }
    return var_3 [ var_0 % 2 ] ;
  }
  