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151. Reverse Words in a String
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:
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A word is defined as a sequence of non-space characters.
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Input string may contain leading or trailing spaces. However, your reversed string should not contain leading or trailing spaces.
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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.
思路分析
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一刷
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/**
* @author D瓜哥 · https://www.diguage.com
* @since 2024-09-19 17:11:20
*/
public String reverseWords(String s) {
Deque<String> stack = new LinkedList<>();
boolean inWord = false;
for (char c : s.toCharArray()) {
if (c == ' ') {
inWord = false;
} else {
if (!inWord) {
stack.push(String.valueOf(c));
inWord = true;
} else {
stack.push(stack.pop() + c);
}
}
}
StringBuilder sb = new StringBuilder(s.length());
while (!stack.isEmpty()) {
sb.append(stack.pop()).append(" ");
}
sb.deleteCharAt(sb.length() - 1);
return sb.toString();
}