Permutations Problem
Description
LeetCode Problem 46.
Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.
Example 1:
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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:
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Input: nums = [0,1]
Output: [[0,1],[1,0]]
Example 3:
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Input: nums = [1]
Output: [[1]]
Constraints:
- 1 <= nums.length <= 6
- -10 <= nums[i] <= 10
- All the integers of nums are unique.
Sample C++ Code
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class Solution {
public:
int n;
vector<vector<int>> ans;
void backtrack(int idx, vector<int>& nums) {
if (idx == n)
ans.push_back(nums);
int tmp;
for (int i = idx; i < n; i ++) {
tmp = nums[i];
nums[i] = nums[idx];
nums[idx] = tmp;
backtrack(idx + 1, nums);
tmp = nums[i];
nums[i] = nums[idx];
nums[idx] = tmp;
}
}
vector<vector<int>> permute(vector<int>& nums) {
n = nums.size();
backtrack(0, nums);
return ans;
}
};