Leetcode 赎金信
利用hash map做
java solution
class Solution {
public boolean canConstruct(String ransomNote, String magazine) {
//首先利用HashMap统计magazine中字符频率
HashMap<Character, Integer> magazinefreq = new HashMap<>();
for(char c : magazine.toCharArray()) {
magazinefreq.put(c, magazinefreq.getOrDefault(c, 0) + 1);
}
for(char c : ransomNote.toCharArray()) {
//如果magazine中都不存在c或者c被用完了
if(!magazinefreq.containsKey(c) || magazinefreq.get(c) == 0) {
return false;
}
magazinefreq.put(c, magazinefreq.get(c) - 1);
}
return true;
}
}