leetcode

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383. Ransom Note

题目

Given two stings ransomNote and magazine, return true if ransomNote can be constructed from magazine and false otherwise.

Each letter in magazine can only be used once in ransomNote.

Example 1:

Input: ransomNote = "a", magazine = "b"
Output: false

Example 2:

Input: ransomNote = "aa", magazine = "ab"
Output: false

Example 3:

Input: ransomNote = "aa", magazine = "aab"
Output: true

Constraints:

• 1 <= ransomNote.length, magazine.length <= 100000
• ransomNote and magazine consist of lowercase English letters.

题目大意

为了不在赎金信中暴露字迹，从杂志上搜索各个需要的字母，组成单词来表达意思。

给你一个赎金信 (ransomNote) 字符串和一个杂志(magazine)字符串，判断 ransomNote 能不能由 magazines 里面的字符构成。

如果可以构成，返回 true ；否则返回 false 。

magazine 中的每个字符只能在 ransomNote 中使用一次。

解题思路

• ransomNote 和 magazine 都是由小写字母组成，所以用数组进行简单的字符统计

代码

package leetcode

func canConstruct(ransomNote string, magazine string) bool {
	if len(ransomNote) > len(magazine) {
		return false
	}
	var cnt [26]int
	for _, v := range magazine {
		cnt[v-'a']++
	}
	for _, v := range ransomNote {
		cnt[v-'a']--
		if cnt[v-'a'] < 0 {
			return false
		}
	}
	return true
}