31. Next Permutation

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LeetCode

Approach: Single Pass Approach link

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class Solution {
    private void swap(int[] nums, int i, int j){
        int temp=nums[i];
        nums[i]=nums[j];
        nums[j]=temp;
    }
    private void reverse(int[] nums,int start,int end){
        while(start<end) swap(nums,start++,end--);
    }
    public void nextPermutation(int[] nums) {
        if(nums==null||nums.length<=1) return;
        int i=nums.length-2;
        while(i>=0&&nums[i]>=nums[i+1]) i--;
        if(i>=0){
            int j=nums.length-1;
            while(j>=0&&nums[j]<=nums[i]) j--;
            swap(nums,i,j);
        }
        reverse(nums,i+1,nums.length-1);
    }
}

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