代码随想录跟刷Day8

---

Leetcode344.反转字符串

直接双指针交换就行了

class Solution {
public:
    void reverseString(vector<char>& s) {
        int left = 0, right = s.size() - 1;
        while(right > left){
            char temp = s[right];
            s[right] = s[left];
            s[left] = temp;
            right--;
            left++;
        }
    }
};

Leetcode541.反转字符串Ⅱ

需要注意s.length()是unsigned int，无符号数，用s.length() - num去判断有可能导致数据溢出，需要避免

class Solution {
public:
    string reverseStr(string s, int k) {
        for(int i = 0; i < s.length(); i += 2 * k){
            int left = i, right = i + k > s.length() ? s.length() - 1: i + k - 1;
            while(right > left){
                char temp = s[right];
                s[right] = s[left];
                s[left] = temp;
                right--;
                left++;
            }
        }
        return s;
    }
};