Given two strings, write a method to decide if one is a permutation of the other.

java

public class Solution {
    public boolean Permutation(String A, String B) {
        if (A == null && B == null) {
            return true;
        }
        if (A == null || B == null) {
            return false;
        }
        if (A.length() != B.length()) {
            return false;
        }
        int[] arr = new int[256];
        for (int i = 0; i < A.length(); i++) {
            arr[A.charAt(i)]++;
        }
        for (int i = 0; i < B.length(); i++) {
            if (--arr[B.charAt(i)] < 0) {
                return false;
            }
        }
        return true;
    }
}
 

public class Solution {
    public List<List<Integer>> subsetsWithDup(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        if (nums == null || nums.length == 0) {
            result.add(new ArrayList<Integer>());
            return result;
        }
        List<Integer> path = new ArrayList<>();
        Arrays.sort(nums);
        dfs(nums, 0, path, result);
        return result;
    }
    private void dfs(int[] nums,
                     int start,
                     List<Integer> path, 
                     List<List<Integer>> result) {
        result.add(new ArrayList<Integer>(path));
        if (start >= nums.length) {
            return;
        }
        for (int i = start; i < nums.length; i++) {
            if (i != start && nums[i] == nums[i - 1]) {
                continue;
            } else {
                path.add(nums[i]);
                dfs(nums, i + 1, path, result);
                path.remove(path.size() - 1);
            }
        }
    }
}
 

Given a list of numbers that may has duplicate numbers, return all possible subsets

有重複元素

java