题解 | #字符串的排列#

public class Solution {
    Set<String> list = new HashSet<>();
    public ArrayList<String> Permutation(String str) {
        char[] c = str.toCharArray();
        StringBuffer sb = new StringBuffer();
       int n = c.length;
       boolean[] isV = new boolean[n];
        dfs(c,isV,0,sb);
        return new ArrayList<>(list);
    }
    public void dfs(char[] c,boolean[] isV,int index,StringBuffer sb){
        if(sb.toString().length() == c.length){
            list.add(sb.toString());
        }
        for(int i = 0;i < c.length;i ++){
            if(isV[i]){
              continue;
            }
            sb.append(c[i]);
            isV[i] = true;
            dfs(c,isV,index+1,sb);
            isV[i] = false;
            sb.deleteCharAt(sb.length()-1);
        }
    }
}