leetcode 344 Reverse String || leetcode 345 Reverse Vowels of a String

leetcode Reverse String

Write a function that takes a string as input and returns the string reversed.

Example: Given s = "hello", return "olleh".

题目地址：leetcode Reverse String

题意:给定一个字符串，让你逆序

思路：

双指针，直接置换

C++

class Solution {
public:
    string reverseString(string s) {
        for(int L = 0,R = s.size()-1; L < R;L++,R--){
            char temp = s[L];
            s[L] = s[R];
            s[R] = temp;
        }
        return s;
    }
};

也可以直接用swap

class Solution {
public:
    string reverseString(string s) {
        for(int L = 0,R = s.size()-1; L < R;L++,R--){
            swap(s[L],s[R]);
        }
        return s;
    }
};

 

Python 直接oneline

class Solution(object):
    def reverseString(self, s):
        """
        :type s: str
        :rtype: str
        """
        return s[::-1]

 

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leetcode  Reverse Vowels of a String

Write a function that takes a string as input and reverse only the vowels of a string.

Example 1: Given s = "hello", return "holle".

Example 2: Given s = "leetcode", return "leotcede".

题目地址：leetcode Reverse Vowels of a String

题意：给定一个字符串，把它的所有元音字母逆序

思路：同样双指针，遇到元音（a,e,i,o,u 注意大小写）就停下来

C++

class Solution {
public:
    bool isVowels(char x){
        x = tolower(x);
        return x =='a'  x== 'e'  x=='i'  x=='o'  x=='u' ;
    }
    
    string reverseVowels(string s) {
        int L = -1,R = s.size(),n =s.size();
        while(L < R){
            while(!isVowels(s[++L]) && L < R);
            while(!isVowels(s[--R]) && R > L);
            if(L >= R) break;    
            swap(s[L], s[R]);
        }
        return s;
    }
};

 

PS:本来不想写题解的，昨天那题太水了= =不过今天又出了一道类似的水题，就一起写了吧

本题是leetcode 344 Reverse String 和 345 Reverse Vowels of a String  题解，

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