ledecode Reverse Words in a String III

557. Reverse Words in a String III

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: "Let's take LeetCode contest"
Output: "s'teL ekat edoCteeL tsetnoc"

Note: In the string, each word is separated by single space and there will not be any extra space in the string.

package leedcode;

class Solution {

    public static void main(String[] args) {
//        String s = "Let's take LeetCode contest";
        String s = "12345";
        System.out.println(s);
        System.out.println(new Solution().reverseWords(s));
    }

    public static void reverseWord(char[] chars, int begin, int end) {

        for (int i = begin; i <= end; i++) {
            char temp = chars[i];
            chars[i] = chars[end];
            chars[end] = temp;
            end--;
        }

    }


    public String reverseWords(String s) {

        char[] chars = s.toCharArray();
        int start = 0;
        int end = 0;

        for (int i = 0; i < chars.length; i++) {

            if (chars[i] == ' ') {
                end = i;
                reverseWord(chars, start, end-1);
                start = end+1;
            }
            end++;
        }

        reverseWord(chars,start,end-1);

        return new String(chars);
    }
}

重新整理逻辑

class Solution {
   
    
      public static void reverseWord(char[] chars, int begin, int end) {

        for (int i = begin; i <= end; i++) {
            char temp = chars[i];
            chars[i] = chars[end];
            chars[end] = temp;
            end--;
        }

    }


    public String reverseWords(String s) {

        char[] chars = s.toCharArray();
        int start = 0;
        int end = 0;

        for (int i = 0; i < chars.length; i++) {
            if (chars[i] == ' ') {
                end = i;
                reverseWord(chars, start, end-1);
                start = end+1;
            } 
            end++;
        }
        
        reverseWord(chars,start,end-1);
        
        return new String(chars);
    }
}