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1002. Find Common Characters

Description

Given a string array words, return an array of all characters that show up in all strings within the words (including duplicates). You may return the answer in any order.

 

Example 1:

Input: words = ["bella","label","roller"]
Output: ["e","l","l"]

Example 2:

Input: words = ["cool","lock","cook"]
Output: ["c","o"]

 

Constraints:

• 1 <= words.length <= 100
• 1 <= words[i].length <= 100
• words[i] consists of lowercase English letters.

Solutions

• Java
• C++
• Python
• Go
• TypeScript

• class Solution {
      public List<String> commonChars(String[] words) {
          int[] cnt = new int[26];
          Arrays.fill(cnt, 10000);
          for (String w : words) {
              int[] ccnt = new int[26];
              for (int i = 0; i < w.length(); ++i) {
                  ++ccnt[w.charAt(i) - 'a'];
              }
              for (int i = 0; i < 26; ++i) {
                  cnt[i] = Math.min(cnt[i], ccnt[i]);
              }
          }
          List<String> ans = new ArrayList<>();
          for (int i = 0; i < 26; ++i) {
              while (cnt[i]-- > 0) {
                  ans.add(String.valueOf((char) (i + 'a')));
              }
          }
          return ans;
      }
  }
  

• class Solution {
  public:
      vector<string> commonChars(vector<string>& words) {
          int cnt[26];
          memset(cnt, 0x3f, sizeof(cnt));
          for (auto& w : words) {
              int ccnt[26]{};
              for (char& c : w) {
                  ++ccnt[c - 'a'];
              }
              for (int i = 0; i < 26; ++i) {
                  cnt[i] = min(cnt[i], ccnt[i]);
              }
          }
          vector<string> ans;
          for (int i = 0; i < 26; ++i) {
              while (cnt[i]--) {
                  ans.emplace_back(1, i + 'a');
              }
          }
          return ans;
      }
  };
  

• class Solution:
      def commonChars(self, words: List[str]) -> List[str]:
          cnt = Counter(words[0])
          for w in words:
              ccnt = Counter(w)
              for c in cnt.keys():
                  cnt[c] = min(cnt[c], ccnt[c])
          ans = []
          for c, v in cnt.items():
              ans.extend([c] * v)
          return ans
  
  

• func commonChars(words []string) (ans []string) {
  	cnt := [26]int{}
  	for i := range cnt {
  		cnt[i] = 1 << 30
  	}
  	for _, w := range words {
  		ccnt := [26]int{}
  		for _, c := range w {
  			ccnt[c-'a']++
  		}
  		for i, v := range cnt {
  			cnt[i] = min(v, ccnt[i])
  		}
  	}
  	for i, v := range cnt {
  		for v > 0 {
  			ans = append(ans, string(i+'a'))
  			v--
  		}
  	}
  	return
  }
  

• function commonChars(words: string[]): string[] {
      const freq: number[] = new Array(26).fill(10000);
      for (const word of words) {
          const t: number[] = new Array(26).fill(0);
          for (const c of word.split('')) {
              ++t[c.charCodeAt(0) - 'a'.charCodeAt(0)];
          }
          for (let i = 0; i < 26; ++i) {
              freq[i] = Math.min(freq[i], t[i]);
          }
      }
      const res: string[] = [];
      for (let i = 0; i < 26; ++i) {
          while (freq[i]-- > 0) {
              res.push(String.fromCharCode(i + 'a'.charCodeAt(0)));
          }
      }
      return res;
  }
  
  

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