Count the number of words in a string, where a word is a contiguous sequence of non-space characters.

Note that you may assume the string does not contain any non-printable characters.

Example:

Input: "Hello, my name is John"
Output: 5
Explanation: A word is a contiguous sequence of non-space characters, so "Hello," counts as one word.

Analysis

#

This problem is somewhat like a state machine. We need to maintain whether the previous character was part of a word. If the previous character is a space and the next one is not, a new word has started.

Rust Code

#

# struct Solution;
impl Solution {
    pub fn count_segments(s: String) -> i32 {
        let mut state = 0;
        let mut res = 0;
        for ch in s.chars() {
            if ch == ' ' {
                state = 0;
            } else {
                if state == 0 {
                    res += 1;
                }
                state = 1;
            }
        }
        res
    }
}