383. Ransom Note

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problem

solution

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class Solution {
public:
    bool canConstruct(string ransomNote, string magazine) {
        int n = ransomNote.size(), m = magazine.size();
        if(n>m) return false;
        vector<int> vec(26,0);
        for(char c:magazine) vec[c-'a']++;
        for(char c:ransomNote){
            vec[c-'a']--;
            if(vec[c-'a']<0) return false;
        }
        return true;
    }
};

analysis

  • time complexity O(n)
  • space complexity O(1)