LeetCode Number of Segments in a String

原题链接在这里：https://leetcode.com/problems/number-of-segments-in-a-string/

题目：

Count the number of segments in a string, where a segment is defined to be a contiguous sequence of non-space characters.

Please note that the string does not contain any non-printable characters.

Example:

Input: "Hello, my name is John"
Output: 5

题解：

使用trim 和 split的到结果.

s = ""时split后的array length 是1.

s开始有空格, e.g. " bc", split后长度是2, ["", "bc"]. 但结束为空格, e.g. "bc ", split 后长度为1, ["bc"].

Time Complexity: O(n), n = s.length(), split用时.

Space: O(n), split后array大小.

AC Java:

1 public class Solution {
2     public int countSegments(String s) {
3         String trimS = s.trim();
4         if(trimS.length() == 0){
5             return 0;
6         }
7         return trimS.split("\\s+").length;
8     }
9 }

当前char不等于' '时，要么当前index为0或者前一位char等于' ', res++.

Time Complexity: O(n). Space: O(1).

AC Java:

1 public class Solution {
2     public int countSegments(String s) {
3         int res = 0;
4         for(int i = 0; i<s.length(); i++){
5             if(s.charAt(i) != ' ' && (i == 0 || s.charAt(i-1) == ' ')){
6                 res++;
7             }
8         }
9         return res;
10     }
11 }