剑指offer58 左旋转字符串 Java

public class LeftReverseString58 {
    public static void main(String[] args) {
        String str = "abcdefg";
        System.out.println(leftReverse(str, 3));
    }

    private static String leftReverse(String str, int n) {
        char[] arr = str.toCharArray();
        reverse(arr, 0, n - 1);
        reverse(arr, n, arr.length - 1);
        reverse(arr, 0, arr.length - 1);
        return new String(arr);
    }

    private static void reverse(char[] arr, int low, int high) {
        while (low < high) {
            swap(arr, low++, high--);
        }
    }

    private static void swap(char[] arr, int i, int j) {
        char temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }


}

解释：逆转左边，逆转右边，整体逆转，bingo