Given an arbitrary ransom note string and another string containing letters from all the magazines, write a function that will return true if the ransom note can be constructed from the magazines ; otherwise, it will return false.
Each letter in the magazine string can only be used once in your ransom note.
Note:
You may assume that both strings contain only lowercase letters.
canConstruct("a", "b") -> false
canConstruct("aa", "ab") -> false
canConstruct("aa", "aab") -> true
bool canConstruct(string ransomNote, string magazine) { map<char, int>mpmag; for (auto ch : magazine)mpmag[ch]++; for (auto ch : ransomNote) { mpmag[ch]--; if (mpmag[ch] < 0)return false; } return true; }
原文：http://www.cnblogs.com/hellowooorld/p/7112992.html