C++刷题使用过的一些套路

int gck(int a, int b) {
	while (a % b > 0) {
		int temp = a % b;
		a = b;
		b = temp;
	}
	
	return b;
} 

void perm(string str, int start) {
	if (start == str.size() - 1) {
		cout << str << endl;
		return ;
	} else {
		for (int i = start; i < str.size(); i++) {
			swap(str[i], str[start]);
			perm(str, start + 1);
			swap(str[i], str[start]);
		}
	}
}

void printAllSon(string str) {
	for (int i = 0; i < str.size(); i++) {
		for (int j = 0; j < str.size() - i; j++) {
			string son = str.substr(i, j + 1);
			cout << son << endl;
		}
	}
} 

//#include <vector>

int binSearchOf(vector<int> &arr, int val) {
	int low = -1, high = arr.size(), mid;
	bool isFind = false;
	
	while (low <= high) {
		mid = (high + low) / 2;
		
		if (arr[mid] < val) {
			low = mid + 1;
		} else if (arr[mid] > val) {
			high = mid - 1;
		} else {
			isFind = true;
			break;
		}
	}
	
	return isFind ? mid : -1;
}

bool isLeap(int year) {
	bool isRight = true;
	
	if (year % 4 != 0) {
		isRight = false;
	} 
	if (year % 100 == 0 && year % 400 != 0) {
		isRight = false;
	}
	
	return isRight;
}

void updateChTo(string &str, char oldCh, char newCh) {
	int pos;
	string goal(1, newCh);
	
	pos = str.find(oldCh);
	while (pos != str.npos) {
		str.replace(pos, 1, goal);
		pos = str.find(oldCh);
	}
}