09 Sept 2026•Easy•Go / Python / TypeScript

Uncommon Words from Two Sentences

Return words that occur exactly once across two sentences combined.

Count all whitespace-separated words from both sentences in one map and keep entries with frequency one.

Complexity

O(n + m) time and O(n + m) space.

Solution files

Go•uncommon-words-from-two-sentences/solution.go

package main

import "strings"

func uncommonFromSentences(s1 string, s2 string) []string {
	counts := map[string]int{}
	for _, word := range strings.Fields(s1 + " " + s2) {
		counts[word]++
	}
	result := []string{}
	for word, count := range counts {
		if count == 1 {
			result = append(result, word)
		}
	}
	return result
}

Python•uncommon-words-from-two-sentences/solution.py

from collections import Counter


class Solution:
    def uncommonFromSentences(self, s1: str, s2: str) -> list[str]:
        counts = Counter((s1 + " " + s2).split())
        return [word for word, count in counts.items() if count == 1]

TypeScript•uncommon-words-from-two-sentences/solution.ts

function uncommonFromSentences(s1: string, s2: string): string[] {
  const counts = new Map<string, number>();
  for (const word of (s1 + " " + s2).split(" ")) counts.set(word, (counts.get(word) ?? 0) + 1);
  return [...counts].filter(([, count]) => count === 1).map(([word]) => word);
}