技術標籤：LeetCode

題目連結

class Solution {
    private void permutationHelper(int len,char[] arr,StringBuilder sb,List<String> ret,int[] vis){
        if(len == arr.length){
            ret.add(sb.toString());
            return;
        }
        for(int i = 0;i < arr.length;i++){
            if
 
(vis[i] == 1)
                continue;
            if(i > 0 && arr[i] == arr[i-1] && vis[i-1] == 1)
                continue;
            sb.append(arr[i]);
            vis[i] = 1;
            permutationHelper(len+1,arr,sb,ret,vis);
            sb.deleteCharAt(sb.length()-1);
            vis[
 
i] = 0;
        }
    }

    public String[] permutation(String s) {
        List<String> ret = new ArrayList<>();
        char[] arr = s.toCharArray();
        int[] vis = new int[arr.length];
        Arrays.sort(arr);
        StringBuilder sb = new StringBuilder();
        permutationHelper
 
(0,arr,sb,ret,vis);
        return ret.toArray(new String[ret.size()]);
    }
}