在最小子集问题中我做错了什么？

Question

极客的代码。

class Solution {

    public int minDiffernce(int arr[], int n) { 
    
        // Your code goes here
        int range = 0;
        for (int i = 0; i < n; i++) {
            range += arr[i];
        }
        boolean[][] dp = new boolean[n+1][range+1];
        for (int i = 0; i <= n + 1; i++) {
            for (int j = 0; j < range + 1; j++) {
                if (i == 0) dp[i][j] = false;
                if (j == 0) dp[i][j] = true;
            }
        }
        
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= range; j++) {
                if (arr[i] <= j){
                    dp[i][j] = dp[i-1][j-arr[i]] || dp[i-1][j];
                }
                else dp[i][j] = dp[i-1][j];
            }
        }
        ArrayList<boolean> v = new ArrayList<boolean>();
        
        for (int i = 0;i < range + 1; i++) {
            if (dp[n][i] == true) v.add(dp[n][i]);
        }
        
        int mini = Integer.MAX_VALUE;
        for (int i = 0; i < range / 2; i++){
            mini = Math.min(mini, range - 2 * v[i]);
        }

        return mini;
    } 
}

它抛出以下错误：

prog.java:53: error: unexpected type
        ArrayList<boolean> v = new ArrayList<boolean>();
                  ^
  required: reference
  found:    boolean
prog.java:53: error: unexpected type
        ArrayList<boolean> v = new ArrayList<boolean>();
                                             ^
  required: reference
  found:    boolean
prog.java:61: error: array required, but ArrayList<<any>> found
            mini = Math.min(mini, range-2*v[i]);
                                           ^

Answer 1

1. ArrayList只能容纳对象，而不能容纳基元类型。因此，它应该是-

ArrayList<Boolean> v = new ArrayList<Boolean>();

1. Math.min()可以有下面提到的四种声明之一。您的代码中的vi将返回布尔值，并且运算结果2*v[i]无效。因此，您可以看到错误。

Math.min(int, int) Math.min(long, long) Math.min(float, float) Math.min(double, double)