LC题解-左旋转字符串

  • 反转区间为前n的子串

  • 反转区间为n到末尾的子串

  • 反转整个字符串

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class Solution {
    public String reverseLeftWords(String s, int n) {
        char[] sc = s.toCharArray();

        // 前 sc.length - n 翻转 
        int l = 0;
        int r = n - 1;
        while(l < r) {
            char t = sc[l];
            sc[l++] = sc[r];
            sc[r--] = t;
        }

        // n 到 结尾翻转
        l = n;
        r = sc.length - 1;
        while(l < r) {
            char t = sc[l];
            sc[l++] = sc[r];
            sc[r--] = t;
        }

        // 全部翻转
        l = 0;
        r = sc.length - 1;
        while(l < r) {
            char t = sc[l];
            sc[l++] = sc[r];
            sc[r--] = t;
        }

        return new String(sc);
    }
}