LeetCode46. 全排列

class Solution {
    public static List<List<Integer>> ans = new ArrayList<List<Integer>>();
    public static int[] path = new int[100];
    public static boolean[] v = new boolean[100];
    public static void dfs(int idx,int[] nums) {
        if(idx >= nums.length) {
            List<Integer> tmp = new ArrayList<Integer>();
            for(int i = 0;i < nums.length;i++)
                tmp.add(nums[path[i]]);
            ans.add(tmp);
            return;
        }
        for(int i = 0;i < nums.length;i++) {
            if(!v[i]) {
                path[idx] = i;
                v[i] = true;
                dfs(idx + 1,nums);
                v[i] = false;
            }
        }
    }
    public List<List<Integer>> permute(int[] nums) {
        ans.clear();
        dfs(0,nums);
        return ans;
    }
}