Next Permutation

class Solution {
    void nextPermutation(int[] arr) {
        int i, n = arr.length;
        for (i = n - 2; i >= 0; i--) {
            if (arr[i] < arr[i + 1])
                break;
        }
        if (i > -1) {
            int nextMax = Integer.MAX_VALUE, nextPos = 0;
            for (int j = i + 1; j < n; j++) {
                if (arr[j] > arr[i] && arr[j] < nextMax) {
                    nextMax = arr[j];
                    nextPos = j;
                }
            }
            int tmp = arr[i];
            arr[i] = arr[nextPos];
            arr[nextPos] = tmp;
            reverse(arr, i + 1, n - 1);
        } else
            reverse(arr, 0, n - 1);
    }

    void reverse(int[] arr, int i, int j) {
        while (i < j) {
            int tmp = arr[i];
            arr[i] = arr[j];
            arr[j] = tmp;
            i++;
            j--;
        }
    }
}