leetcode_383. Ransom Note-近似子串问题

典型的近似子串问题！

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

给你左右两个字符串，判断左侧子串是否可以由右侧字符串中抽取部分字符得到（右侧字符串每个字母仅可用一次），全都是小写字母。

思路：建立数组存储每个字母出现的次数

public boolean canConstruct(String ransomNote, String magazine) {        int[] letter = new int[26];        for(int i=0;i<magazine.length();i++)            letter[magazine.charAt(i)-'a']++;        for(int i=0;i<ransomNote.length();i++)            letter[ransomNote.charAt(i)-'a']--;        for(int i=0;i<26;i++)            if(letter[i]<0)                return false;        return true;    }