Number of Segments in a String

LeetCode 434 · View on LeetCode

Count the number of segments (contiguous non-space characters) in a string.

Solution 1: strings.Fields (one-liner)

package main

import (
	"fmt"
	"strings"
)

func countSegments(s string) int {
	return len(strings.Fields(s))
}

func main() {
	fmt.Println(countSegments("Hello   World  Go")) // 3
}

strings.Fields splits by any whitespace and ignores consecutive spaces — no empty strings.

Solution 2: Split and filter

func countSegments(s string) int {
	sArr := strings.Split(s, " ")
	seg := 0
	for _, w := range sArr {
		if strings.Trim(w, " ") != "" {
			seg++
		}
	}
	return seg
}

strings.Split produces empty strings for consecutive spaces, so we filter them out. Allocates a slice.

Solution 3: Single pass — count word starts

func countSegments(s string) int {
	segment := 0
	for i, ch := range s {
		if ch != ' ' && (i == 0 || s[i-1] == ' ') {
			segment++
		}
	}
	return segment
}

Detects the start of each word: a non-space character where the previous character was a space (or it's the first character). O(n) time, O(1) space, no allocations.