Leetcode (Sword finger offer) - 58 - ii Rotate string left

Topic link ： Click to open the link

The main idea of the topic ： A little .

Their thinking ： A little .

Related enterprises

• Bytes to beat

AC Code

• Java

//  Solution (1)
class Solution {
    public String reverseLeftWords(String s, int n) {
        return s.substring(n) + s.substring(0, n);
    }
}

//  Solution (2)
class Solution {
    public String reverseLeftWords(String s, int n) {
        StringBuilder res = new StringBuilder();
        for(int i = n; i < s.length(); i++)
            res.append(s.charAt(i));
        for(int i = 0; i < n; i++)
            res.append(s.charAt(i));
        return res.toString();
    }
}

//  Solution (3)
class Solution {
    public String reverseLeftWords(String s, int n) {
        StringBuilder res = new StringBuilder();
        for(int i = n; i < n + s.length(); i++)
            res.append(s.charAt(i % s.length()));
        return res.toString();
    }
}

• C++ 

//  Solution (1)
class Solution {
public:
    string reverseLeftWords(string s, int n) {
        return s.substr(n, s.size()) + s.substr(0, n);
    }
};

//  Solution (2)
class Solution {
public:
    string reverseLeftWords(string s, int n) {
        reverseString(s, 0, n - 1);
        reverseString(s, n, s.size() - 1);
        reverseString(s, 0, s.size() - 1);
        return s;
    }
private:
    void reverseString(string& s, int i, int j) {
        while(i < j) swap(s[i++], s[j--]);
    }
};

//  Solution (3)
class Solution {
public:
    string reverseLeftWords(string s, int n) {
        reverse(s.begin(), s.begin() + n);
        reverse(s.begin() + n, s.end());
        reverse(s.begin(), s.end());
        return s;
    }
};