CF1389A-LCM Problem

题目:

题目描述:

Let $ LCM(x, y) $ be the minimum positive integer that is divisible by both $ x $ and $ y $ . For example, $ LCM(13, 37) = 481 $ , $ LCM(9, 6) = 18 $ .

You are given two integers $ l $ and $ r $ . Find two integers $ x $ and $ y $ such that $ l \le x < y \le r $ and $ l \le LCM(x, y) \le r $ .

输入格式:

The first line contains one integer $ t $ ( $ 1 \le t \le 10000 $ ) — the number of test cases.

Each test case is represented by one line containing two integers $ l $ and $ r $ ( $ 1 \le l < r \le 10^9 $ ).

输出格式:

For each test case, print two integers:

• if it is impossible to find integers $ x $ and $ y $ meeting the constraints in the statement, print two integers equal to $ -1 $ ;
• otherwise, print the values of $ x $ and $ y $ (if there are multiple valid answers, you may print any of them).

样例:

样例输入 1:

1
2
3
4
5

4
1 1337
13 69
2 4
88 89

样例输出 1:

1
2
3
4

6 7
14 21
2 4
-1 -1

思路:

实现:

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#include "ybwhead/ios.h"
int main()
{
    int TTT;
    yin >> TTT;
    while (TTT--)
    {
        int l, r;
        yin >> l >> r;
        if (r < 2 * l)
            yout << -1 << ' ' << -1 << endl;
        else
            yout << l << ' ' << 2 * l << endl;
    }
    return 0;
}