剑指 Offer 58 - II. 左旋转字符串

剑指 Offer 58 - II. 左旋转字符串

1. 翻转前n个字符
2. 翻转其余字符
3. 翻转所有字符

class Solution {
    public String reverseLeftWords(String s, int n) {
        char[] ch = s.toCharArray();
        reverse(ch, 0, n - 1);
        reverse(ch, n, ch.length - 1);
        reverse(ch, 0, ch.length - 1);
        return new String(ch);
    }

    void reverse(char[] ch, int l, int r){
        while(l < r){
            char tmp = ch[l];
            ch[l] = ch[r];
            ch[r] = tmp;
            l++;
            r--;
        }
    }
}