Solution 1 - Min Frequency Intersection

Take per-character minimum count across all words.

TimeComplexity: O(total\_chars)

SpaceComplexity: O(1)

""" 1002.1 - Find Common Characters - Solution 1 - Min Frequency Intersection """

from collections import Counter
from typing import List

class Solution:
    def commonChars(self, words: List[str]) -> List[str]:
        c = Counter(words[0])
        for w in words[1:]:
            c &= Counter(w)
        return list(c.elements())

function commonChars(words){
 let c=new Array(26).fill(Infinity);
 for(const w of words){
  const d=new Array(26).fill(0);
  for(const ch of w) d[ch.charCodeAt(0)-97]++;
  for(let i=0;i<26;i++) c[i]=Math.min(c[i],d[i]);
 }
 const out=[];
 for(let i=0;i<26;i++) for(let k=0;k<c[i];k++) out.push(String.fromCharCode(97+i));
 return out;
}

function commonChars(words:string[]):string[]{
 let c:number[]=new Array(26).fill(Infinity);
 for(const w of words){
  const d:number[]=new Array(26).fill(0);
  for(const ch of w) d[ch.charCodeAt(0)-97]++;
  for(let i=0;i<26;i++) c[i]=Math.min(c[i],d[i]);
 }
 const out:string[]=[];
 for(let i=0;i<26;i++) for(let k=0;k<c[i];k++) out.push(String.fromCharCode(97+i));
 return out;
}

package main

func commonChars(words []string) []string {
	cnt := make([]int, 26)
	for i := range cnt { cnt[i] = 1<<30 }

	for _, w := range words {
		d := make([]int, 26)
		for i := 0; i < len(w); i++ {
			d[w[i]-'a']++
		}
		for i := 0; i < 26; i++ {
			if d[i] < cnt[i] { cnt[i] = d[i] }
		}
	}

	out := []string{}
	for i := 0; i < 26; i++ {
		for k := 0; k < cnt[i]; k++ {
			out = append(out, string(byte('a'+i)))
		}
	}
	return out
}

func main() {}

fn common_chars(words: &[&str]) -> Vec<char> {
	let mut cnt = [usize::MAX; 26];
	for w in words {
		let mut d = [0usize; 26];
		for b in w.bytes() { d[(b - b'a') as usize] += 1; }
		for i in 0..26 { cnt[i] = cnt[i].min(d[i]); }
	}
	let mut out = vec![];
	for i in 0..26 { for _ in 0..cnt[i] { out.push((b'a'+i as u8) as char); } }
	out
}
fn main() {}

1002 - Find Common Characters

Solution 1 - Min Frequency Intersection