题目讲解

1419. 数青蛙

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算法讲解

class Solution {
public:int minNumberOfFrogs(string croakOfFrogs) {string target = "croak";int n = target.size();//保存target每个字符的位置indexunordered_map<char, int>index;for(int i = 0; i < n; i++)index[target[i]] = i;//按照target的顺序制作Hashvector<int>Hash(n); for(int i = 0; i < croakOfFrogs.size(); i++){if(croakOfFrogs[i] == 'c'){if(Hash[n-1] != 0)Hash[n-1]--;Hash[0]++;}else{//获取当前 croak 字母的下标int char_index = index[croakOfFrogs[i]];//判断前一个字符是否在Hash中出现 if(Hash[char_index - 1] == 0)return -1;Hash[char_index - 1]--; Hash[char_index]++;}}//怕出现这种croakcrofor(int i = 0; i < n-1; i++){if(Hash[i] != 0)return -1;}return Hash[n-1];}
};