PTA甲级考试真题练习96——1096 Consecutive Factors

题目

思路

对于每个质因子（小于等于num）i，从i开始遍历直到乘积不能被整除，记录其中最大序列

坑点

注意不要忽略为质数的情况，应该就输出质数本身，否则最后两个测试点运行超时

代码

#include <iostream>
using namespace std;
int main()
{
	int num;
	int maxlen = 0;
	int start, end;
	cin >> num;
	int sqrtn = sqrt((double)num);
	for (int i = 2; i <= sqrtn; ++i) {
		if (num % i != 0)
			continue;
		int j = i;
		int k = j;
		while (true) {
			k *= j + 1;
			if (num % k != 0) break;
			j++;
		}
		if (j -i + 1 > maxlen) {
			maxlen = j - i + 1;
			start = i;
			end = j;
		}
	}
    if(maxlen == 0){
        cout<<1<<endl;
        cout<<num;
        return 0;
    }
	cout << maxlen << endl;
	cout << start;
	for (int i = start+1; i <= end; ++i) {
		cout << "*" << i;
	}
	return 0;
}