Leetcode: Number of Segments in a String

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

 用split()

public class Solution {
    public int countSegments(String s) {
        if (s==null || s.length()==0) return 0;
        String[] strs = s.split(" ");
        int count = 0;
        for (String str : strs) {
            if (str.length() != 0) count++;
        }
        return count;
    }
}

 不用API, better solution, O(N) time O(1) space

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;
}