topic
Given an array nums without repeating numbers, return all possible permutations of it. You can return answers in any order.
Example 1:
Input: nums = [1,2,3]
Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1 ,2],[3,2,1]]
Example 2:
Input: nums = [0,1]
Output: [[0,1],[1,0]]
Example 3:
Input: nums = [1]
Output: [[1]]
Hint:
1 <= nums.length <= 6
-10 <= nums[i] <= 10
all integers in nums are different from each other
answer
The initial judgment uses depth traversal, that is, recursion.
Three elements of recursive function: parameter recursive boundary recursive entry
parameter: parameter uses an array to represent the currently selected number
Recursive boundary: when all the numbers in the array are selected, return to the previous
recursive entry: recursion has 3 entries 1 , 2, 3. (note the constraints)
code
var permute = function(nums) {
//用于判断是否标记
let use = {};
//保存结果
let ans = [];
function dfs(path)
{
//递归边界
if(path.length==nums.length)
{
ans.push(path.slice());
return ;
}
//递归选择
for(let i = 0; i < nums.length; i++)
{
if(use[i])
continue;
path.push(nums[i]);
use[i] = true;
dfs(path);
path.pop();
use[i] = false;
}
}
dfs([])
return ans;
};