给定一个字符串，找出字符串中包含｛’a’,’b’,’c’｝字符集的最短子串

#include<string>
using namespace std;

struct Record{
	bool isAppear;
	int lastPos;
};

map<char, Record> mp;
int front, rear;
int minLength;

string str = "ababaaassaxxxaaacccd";
char charset[3] = {'a', 'b', 'c'};

bool (){
	for(auto it = mp.begin();it != mp.end(); it++){
		if(!it->second.isAppear){
			return false;
		}
	}
	return true;
}

void updateFront(int pos){
	front = pos + 1;
	mp[str[pos]].isAppear = false;
}

int countLength(){
	int max = -1, min = INT_MAX;
	for(auto it = mp.begin(); it != mp.end(); it++){
		if(it->second.lastPos > max)
			max = it->second.lastPos;
		if(it->second.lastPos < min)
			min = it->second.lastPos;
	}
	updateFront(min);
	return max - min + 1;
}

int main(){
	
	for(int i = 0; i < 3; i++){
		Record r;
		r.isAppear = false;
		mp[charset[i]] = r;
	}
	front = 0, rear = 0;
	minLength = INT_MAX;

	for(; rear < str.length(); rear++){
		if(mp.find(str[rear]) != mp.end()){
			mp[str[rear]].isAppear = true;
			mp[str[rear]].lastPos = rear;
			if(isValid()){
				int len = countLength();
				minLength = len < minLength ? len : minLength;
			}
		}
	}
	printf("minLength = %dn", minLength);
	return 0;
}