Codeforces Round 887 (Div. 1)
A
Ntarsis' Set
Codeforces
1800
原题
←B →
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Ntarsis has been given a set $S$, initially containing integers $1, 2, 3, \ldots, 10^{1000}$ in sorted order. Every day, he will remove the $a_1$-th, $a_2$-th, $\ldots$, $a_n$-th smallest numbers in $S$ simultaneously.

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What is the smallest element in $S$ after $k$ days?

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Input

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Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 10^5$). The description of the test cases follows.

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The first line of each test case consists of two integers $n$ and $k$ ($1 \leq n,k \leq 2 \cdot 10^5$) — the length of $a$ and the number of days.

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The following line of each test case consists of $n$ integers $a_1, a_2, \ldots, a_n$ ($1 \leq a_i \leq 10^9$) — the elements of array $a$.

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It is guaranteed that:

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  • The sum of $n$ over all test cases won't exceed $2 \cdot 10^5$;
  • The sum of $k$ over all test cases won't exceed $2 \cdot 10^5$;
  • $a_1 \lt a_2 \lt \cdots \lt a_n$ for all test cases.
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Output

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For each test case, print an integer that is the smallest element in $S$ after $k$ days.

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Note

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For the first test case, each day the $1$-st, $2$-nd, $4$-th, $5$-th, and $6$-th smallest elements need to be removed from $S$. So after the first day, $S$ will become $\require{cancel}$ $\{\cancel 1, \cancel 2, 3, \cancel 4, \cancel 5, \cancel 6, 7, 8, 9, \ldots\} = \{3, 7, 8, 9, \ldots\}$. The smallest element is $3$.

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For the second case, each day the $1$-st, $3$-rd, $5$-th, $6$-th and $7$-th smallest elements need to be removed from $S$. $S$ will be changed as follows:

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Day$S$ before$S$ after1$\{\cancel 1, 2, \cancel 3, 4, \cancel 5, \cancel 6, \cancel 7, 8, 9, 10, \ldots \}$$\to$$\{2, 4, 8, 9, 10, \ldots\}$2$\{\cancel 2, 4, \cancel 8, 9, \cancel{10}, \cancel{11}, \cancel{12}, 13, 14, 15, \ldots\}$$\to$$\{4, 9, 13, 14, 15, \ldots\}$3$\{\cancel 4, 9, \cancel{13}, 14, \cancel{15}, \cancel{16}, \cancel{17}, 18, 19, 20, \ldots\}$$\to$$\{9, 14, 18, 19, 20, \ldots\}$

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The smallest element left after $k = 3$ days is $9$.

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样例

Input #1
7
5 1
1 2 4 5 6
5 3
1 3 5 6 7
4 1000
2 3 4 5
9 1434
1 4 7 9 12 15 17 18 20
10 4
1 3 5 7 9 11 13 15 17 19
10 6
1 4 7 10 13 16 19 22 25 28
10 150000
1 3 4 5 10 11 12 13 14 15
Output #1
3
9
1
12874
16
18
1499986
InputCopy OutputCopy
题目信息
题号
1852A
时间限制
2 s
内存限制
256 MB
标签
二分
数学
数论

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