C. Quick coffee

Codeforces

IDCF10241C

Time1000ms

Memory256MB

Difficulty—

English · Original

Formal · Original

Let's say we would like to give change of $d$ dollars after a puchase of coffee. The only coins that we can use have values $a$, $a + 1$, ..., $b$. Is it possible to give out the change? We are interested in even harder quesion: for given $d$ and $a$ what is the smallest $b$ such that the change can be given? The input is two numbers $1 <= a <= d <= 10^9$. Print smallest $b$ such that $d$ is a sum of coins from range $a,..., b$. ## Input The input is two numbers $1 <= a <= d <= 10^9$. ## Output Print smallest $b$ such that $d$ is a sum of coins from range $a,..., b$. [samples]

**Definitions** Let $ t \in \mathbb{Z} $ be the number of test cases. For each test case $ k \in \{1, \dots, t\} $, let $ n_k \in \mathbb{Z} $ be the target value. Initial state: $ a = 1 $, $ x = 0 $. **Operations** In one operation, choose one of: 1. $ x \leftarrow x + a $ 2. $ a \leftarrow x $, then $ x \leftarrow x + a $ **Objective** For each $ n_k $, find the minimum number of operations to reach $ x = n_k $.

API Response (JSON)

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