【LeetCode】 151. Reverse Words in a String 翻转字符串里的单词（Medium）（JAVA）
题目地址: https://leetcode.com/problems/reverse-words-in-a-string/
题目描述：
Given an input string, reverse the string word by word.
Example 1:
Input: "the sky is blue"
Output: "blue is sky the"
Example 2:
Input: " hello world! "
Output: "world! hello"
Explanation: Your reversed string should not contain leading or trailing spaces.
Example 3:
Input: "a good example"
Output: "example good a"
Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.
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) extra space.
题目大意
给定一个字符串，逐个翻转字符串中的每个单词。
解题方法
比较简单，只要注意第一个单词后面没有空格即可
class Solution {
public String reverseWords(String s) {
StringBuilder sb = new StringBuilder();
int count = 0;
for (int i = 0; i < s.length(); i++) {
if (s.charAt(i) == ' ') {
if (count > 0) {
if (sb.length() > 0) {
sb.insert(0, s.substring(i - count, i) + " ");
} else {
sb.append(s.substring(i - count, i));
}
}
count = 0;
} else {
count++;
}
}
if (count > 0) {
if (sb.length() > 0) {
sb.insert(0, s.substring(s.length() - count, s.length()) + " ");
} else {
sb.append(s.substring(s.length() - count, s.length()));
}
}
return sb.toString();
}
}
执行用时 : 6 ms, 在所有 Java 提交中击败了 49.40% 的用户
内存消耗 : 39.4 MB, 在所有 Java 提交中击败了 5.41% 的用户