Leetcode:47. Permutations II

Description

Description

Given a collection of distinct numbers, return all possible permutations.

Example

For example,
[1,1,2] have the following unique permutations:

[
[1,1,2],
[1,2,1],
[2,1,1]
]

思路

题一读完，感觉和46题可以使用同样的代码

一提交，AC，呵呵哒。。

代码

class Solution {
public:
vector<vector<int>> permuteUnique(vector<int>& nums) {
vector<vector<int>> res;
int len = nums.size();
if(len == 0) return res;
if(len == 1) {
res.push_back(nums);
return res;
}

sort(nums.begin(), nums.end());

do{
res.push_back(nums);
}
while(getNextPermute(nums, len));

return res;
}

bool getNextPermute(vector<int>& nums, int len){
int index1 = 0, index2 = -1, flag = nums[0];
for(int i = 1; i < len; ++i){
if(nums[i] > nums[i - 1]){
index1 = i - 1;
index2 = i;
flag = nums[i] - nums[i - 1];
}
else if(nums[i] > nums[index1] && nums[i] - nums[index1] < flag){
index2 = i;
flag = nums[i] - nums[index1];
}
}

if(index2 == -1) return false;

swap(nums[index1], nums[index2]);
sort(nums.begin() + index1 + 1, nums.end());
return true;
}
};