A14552. The Miracle and the Sleeper
编程题
普及/提高-
知识点
题目描述
You are given two integers $l$ and $r$ , $l\le r$ . Find the largest possible value of $a \bmod b$ over all pairs $(a, b)$ of integers for which $r\ge a \ge b \ge l$ .
As a reminder, $a \bmod b$ is a remainder we get when dividing $a$ by $b$ . For example, $26 \bmod 8 = 2$ .
As a reminder, $a \bmod b$ is a remainder we get when dividing $a$ by $b$ . For example, $26 \bmod 8 = 2$ .
输入格式
Each test contains multiple test cases.
The first line contains one positive integer $t$ $(1\le t\le 10^4)$ , denoting the number of test cases. Description of the test cases follows.
The only line of each test case contains two integers $l$ , $r$ ( $1\le l \le r \le 10^9$ ).
The first line contains one positive integer $t$ $(1\le t\le 10^4)$ , denoting the number of test cases. Description of the test cases follows.
The only line of each test case contains two integers $l$ , $r$ ( $1\le l \le r \le 10^9$ ).
输出格式
For every test case, output the largest possible value of $a \bmod b$ over all pairs $(a, b)$ of integers for which $r\ge a \ge b \ge l$ .
输入输出样例
输入 #1
4 1 1 999999999 1000000000 8 26 1 999999999
输出 #1
0 1 12 499999999
说明/提示
In the first test case, the only allowed pair is $(a, b) = (1, 1)$ , for which $a \bmod b = 1 \bmod 1 = 0$ .
In the second test case, the optimal choice is pair $(a, b) = (1000000000, 999999999)$ , for which $a \bmod b = 1$ .
In the second test case, the optimal choice is pair $(a, b) = (1000000000, 999999999)$ , for which $a \bmod b = 1$ .