LeetCode: Find All Numbers Disappeared in an Array

这题考的是桶排序，知道的很简单，不知道的话就很难

public class Solution {
    public List<Integer> findDisappearedNumbers(int[] nums) {
        int a = 0;
        int b = 0;
        for (int i = 0; i < nums.length; i++) {
            while (nums[i] != nums[nums[i]-1]) {
                a = nums[i];
                b = nums[nums[i]-1];
                nums[nums[i]-1] = a;
                nums[i] = b;
            }
        }
        List<Integer> ans = new ArrayList<Integer>();
        for (int i = 0; i < nums.length; i++) {
            if (nums[i] != i+1) ans.add(i+1);
        }
        return ans;
    }
}