Leetcode--Next permutation

Title Description:


Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.


If Such arrangement is not a possible, it must rearrange it as the lowest possible order (ie, sorted in ascending order).


The replacement must is in-place, do not allocate extra memory.


Here is some examples. Inputs is in the left-hand column and its corresponding outputs is in the right-hand column.
1,2,3→1,3,2
3,2,1→1,2,3
1,1,5→1,5,1


Given a sequence, find the next sort.


Ideas:


Will index, INDEX2 =-1;
1. From right to left, if not satisfied num[i+1] < num [I],index = i;
2. Then find the number of the first num[i] > Num[index] from right to left, index 2 = i;
3. Exchange Num[index] and NUM[INDEX2]
4. Reverse the number of num[index+1. N].


Implementation code:

public class Solution {public    void Nextpermutation (int[] nums) {        var index =-1;    for (var i = nums. Length-1; i > 0; i--) {    if (Nums[i] > Nums[i-1]) {    index = i-1;    break;    }    }        var index2 =-1;    if (Index! =-1) {for    (var i = nums. Length-1; I >= 0; i--) {    if (Nums[i] > Nums[index]) {    index2 = i;    Break    ;            }}} if (Index! =-1 && index2! =-1) {    var t = Nums[index];    Nums[index] = Nums[index2];    NUMS[INDEX2] = t;    }        var k = index + 1;    var j = Nums. Length-1;        while (K < j) {    var tmp = nums[k];    NUMS[K] = nums[j];    NUMS[J] = tmp;        k++;    j--;}}}    

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Leetcode--Next permutation