Problem:
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.
You may assume that both strings contain only lowercase letters.
canConstruct("a", "b") -> false
canConstruct("aa", "ab") -> false
canConstruct("aa", "aab") -> true
Summary:
给出两个字符串r，m，判断r串能否由m串组成。即r串中的所有字母包含在m串中即可。
Analysis:
Hash表
1 class Solution { 2 public: 3 bool canConstruct(string ransomNote, string magazine) { 4 int magChar[26] = {0}; 5 int len = magazine.size(); 6 for (int i = 0; i < len; i++) { 7 magChar[magazine[i] - 'a']++; 8 } 9 10 len = ransomNote.size(); 11 for (int i = 0; i < len; i++) { 12 if (--magChar[ransomNote[i] - 'a'] < 0) { 13 return false; 14 } 15 } 16 17 return true; 18 } 19 };