數據結構和算法之數組右移K

基本思路：不開闢新的數組空間的情況下考慮在原屬組上進行操作

1. 將數組倒置，這樣後k個元素就跑到了數組的前面，然後反轉一下即可
2. 同理後 len-k個元素只需要翻轉就完成數組的k次移動

public class ArrayKShift {

    public void arrayKShift(int[] array, int k) {

        /**
         * constrictions
         */

        if (array == null || 0 == array.length) {
            return ;
        }

        k = k % array.length;

        if (0 > k) {
            return;
        }


        /**
         * reverse array , e.g: [1, 2, 3 ,4] to [4,3,2,1]
         */

        for (int i = 0; i < array.length / 2; i++) {
            int tmp = array[i];
            array[i] = array[array.length - 1 - i];
            array[array.length - 1 - i] = tmp;
        }

        /**
         * first k element reverse
         */
        for (int i = 0; i < k / 2; i++) {
            int tmp = array[i];
            array[i] = array[k - 1 - i];
            array[k - 1 - i] = tmp;
        }

        /**
         * last length - k element reverse
         */

        for (int i = k; i < k + (array.length - k ) / 2; i ++) {
            int tmp = array[i];
            array[i] = array[array.length - 1 - i + k];
            array[array.length - 1 - i + k] = tmp;
        }
    }

    public static void main(String[] args) {
        int[] array = {1, 2, 3 ,4, 5, 6, 7};
        ArrayKShift shift = new ArrayKShift();
        shift.arrayKShift(array, 6);

        Arrays.stream(array).forEach(o -> {
            System.out.println(o);
        });

    }
}