问题描述
https://leetcode.com/problems/next-permutation/
解决思路
不太会，没能理解。只能先把代码贴上来。
问题解惑
代码
class Solution {
public void nextPermutation(int[] nums) {
if(nums == null || nums.length == 0) return;
int firstSmall = -1;
for(int i = nums.length - 2; i >= 0; i--){
if(nums[i] < nums[i + 1]){
firstSmall = i;
break;
}
}
if(firstSmall == -1){
reverse(nums, 0, nums.length - 1);
return;
}
int firstLarge = -1;
for(int i = nums.length - 1; i > firstSmall; i--){
if(nums[i] > nums[firstSmall]){
firstLarge = i;
break;
}
}
swap(nums, firstSmall, firstLarge);
reverse(nums, firstSmall + 1, nums.length - 1);
return;
}
public void swap(int[] nums, int i, int j){
int temp = nums[i];
nums[i++] = nums[j];
nums[j++] = temp;
}
public void reverse(int[] nums, int i, int j){
while(i < j){
swap(nums, i++, j--);
}
}
}
