leetCode_daysWORK/Next Permutation.java at main · Deep8595/leetCode_daysWORK · GitHub

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class Solution {
    public void nextPermutation(int[] nums) {
        int i = nums.length - 2;

        while( i >= 0 && nums[i] >= nums[i+1]){
            i--;
        }
        if( i == -1){
            reverse( nums, 0, nums.length -1 );
            return;
        }
        int j = nums.length-1;
        while( nums[i] >= nums[j]){
            j--;
        }
        swap( nums, i, j);
        reverse(nums, i+1, nums.length -1);
    }

        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);
                start++;
                end--;
            }
        }


}