51. numerical arrangement

Catalog

One 、 Problem description

Two 、 Problem solving

1. Code

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One 、 Problem description

Enter a set of numbers （ May contain duplicate numbers ）, Output all its permutations .

Data range

Enter the array length [0,6].

Examples

 Input ：[1,2,3]

 Output ：
      [
        [1,2,3],
        [1,3,2],
        [2,1,3],
        [2,3,1],
        [3,1,2],
        [3,2,1]
      ]

Two 、 Problem solving

1. Code

class Solution {
public:
    vector<vector<int>> permutation(vector<int>& nums) {
        sort(nums.begin(),nums.end());
        vector<vector<int>> res;
        do
        {
            res.push_back(nums);
        }while(next_permutation(nums.begin(),nums.end()));
        
        return res;
    }
};

next_permutation()

Rearrange elements in scope [first,last) For the next Dictionary order Bigger array . Permutation is every possible permutation of elements （ among N Is the number of elements in the range ）. According to them Dictionaries Sort different permutations by comparing them with each other ; The first possible arrangement in this order （ Press The dictionary order is smaller than Permutations of all other permutations ） Is an arrangement of all elements in ascending order , The largest arrangement is that all elements are arranged in descending order .  The comparison of individual elements is done using one of the following methods N!