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:

public class Solution {
    public int countSegments(String s) {
        String trimS = s.trim();
        if(trimS.length() == 0){
            return 0;
        }
        return trimS.split("\\s+").length;
    }
}

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:

public class Solution {
    public int countSegments(String s) {
        int res = 0;
        for(int i = 0; i<s.length(); i++){
            if(s.charAt(i) != ' ' && (i == 0 || s.charAt(i-1) == ' ')){
                res++;
            }
        }
        return res;
    }
}