LeetCode 0151 - Reverse Words in a String

Reck Zhang

发布于 2021-08-11 14:48:42

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发布于 2021-08-11 14:48:42

文章被收录于专栏：Reck Zhang

Reverse Words in a String

Desicription

Given an input string, reverse the string word by word.

Example:

Input: "the sky is blue",
Output: "blue is sky the".

Note:

A word is defined as a sequence of non-space characters.
Input string may contain leading or trailing spaces. However, your reversed string should not contain leading or trailing spaces.
You need to reduce multiple spaces between two words to a single space in the reversed string.

Follow up: For C programmers, try to solve it in-place in O(1) space.

Solution

class Solution {
public:
    void reverseWords(string &s) {
        string res;
        int right = s.size();
        for(int left = right - 1; left >= 0; left--) {
            if(s[left] == ' ')
                right = left;
            else if(left == 0 || s[left-1] == ' ') {
                if(res.size())
                    res += " ";
                res += s.substr(left, right-left);
            }
        }
        s = res;
    }
};

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