leetcode refers to Offer 58 - II. Left Rotate String

字符串的左旋转操作是把字符串前面的若干个字符转移到字符串的尾部.请定义一个函数实现字符串左旋转操作的功能.比如,输入字符串"abcdefg"和数字2,该函数将返回左旋转两位得到的结果"cdefgab".

示例 1：

输入: s = “abcdefg”, k = 2
输出: “cdefgab”
示例 2：

输入: s = “lrloseumgh”, k = 6
输出: “umghlrlose”

限制：

1 <= k < s.length <= 10000

class Solution {
    
public:
    string reverseLeftWords(string s, int n) {
    
        string res=s;  //保证res和s的元素个数相同
        int m=s.length();
        for(int i=0;i<m;++i)
            res[i]=s[(i+n)%m];  //In the process of adding later, the length of the string may be exceeded,So go to the mold and go back to the original position
        return res;
    }
};

class Solution {
    
public:
    string reverseLeftWords(string s, int n) {
    
        string s1="",s2="";
        for(int i=1;i<=n;++i)
            s1+=s[i-1];
        for(int i=n+1;i<=s.length();++i)
            s2+=s[i-1];
        s2+=s1;
        return s2;
    }
};