A14791 | Fun with Even Subarrays
时间限制1s
内存限制256MB
通过 / 提交0/0
题目描述
You are given an array $a$ of $n$ elements. You can apply the following operation to it any number of times:
- Select some subarray from $a$ of even size $2k$ that begins at position $l$ ( $1\le l \le l+2\cdot{k}-1\le n$ , $k \ge 1$ ) and for each $i$ between $0$ and $k-1$ (inclusive), assign the value $a_{l+k+i}$ to $a_{l+i}$ .
For example, if $a = [2, 1, 3, 4, 5, 3]$ , then choose $l = 1$ and $k = 2$ , applying this operation the array will become $a = [3, 4, 3, 4, 5, 3]$ .
Find the minimum number of operations (possibly zero) needed to make all the elements of the array equal.
- Select some subarray from $a$ of even size $2k$ that begins at position $l$ ( $1\le l \le l+2\cdot{k}-1\le n$ , $k \ge 1$ ) and for each $i$ between $0$ and $k-1$ (inclusive), assign the value $a_{l+k+i}$ to $a_{l+i}$ .
For example, if $a = [2, 1, 3, 4, 5, 3]$ , then choose $l = 1$ and $k = 2$ , applying this operation the array will become $a = [3, 4, 3, 4, 5, 3]$ .
Find the minimum number of operations (possibly zero) needed to make all the elements of the array equal.
输入格式
The input consists of multiple test cases. The first line contains a single integer $t$ ( $1 \leq t \leq 2 \cdot 10^4$ ) — the number of test cases. Description of the test cases follows.
The first line of each test case contains an integer $n$ ( $1 \leq n \leq 2 \cdot 10^5$ ) — the length of the array.
The second line of each test case consists of $n$ integers $a_1, a_2, \dots, a_n$ ( $1 \leq a_i \leq n$ ) — the elements of the array $a$ .
It is guaranteed that the sum of $n$ over all test cases does not exceed $2 \cdot 10^5$ .
The first line of each test case contains an integer $n$ ( $1 \leq n \leq 2 \cdot 10^5$ ) — the length of the array.
The second line of each test case consists of $n$ integers $a_1, a_2, \dots, a_n$ ( $1 \leq a_i \leq n$ ) — the elements of the array $a$ .
It is guaranteed that the sum of $n$ over all test cases does not exceed $2 \cdot 10^5$ .
输出格式
Print $t$ lines, each line containing the answer to the corresponding test case — the minimum number of operations needed to make equal all the elements of the array with the given operation.
输入输出样例
输入 #1
5 3 1 1 1 2 2 1 5 4 4 4 2 4 4 4 2 1 3 1 1
输出 #1
0 1 1 2 0
In the first test, all elements are equal, therefore no operations are needed.
In the second test, you can apply one operation with $k=1$ and $l=1$ , set $a_1 := a_2$ , and the array becomes $[1, 1]$ with $1$ operation.
In the third test, you can apply one operation with $k=1$ and $l=4$ , set $a_4 := a_5$ , and the array becomes $[4, 4, 4, 4, 4]$ .
In the fourth test, you can apply one operation with $k=1$ and $l=3$ , set $a_3 := a_4$ , and the array becomes $[4, 2, 3, 3]$ , then you can apply another operation with $k=2$ and $l=1$ , set $a_1 := a_3$ , $a_2 := a_4$ , and the array becomes $[3, 3, 3, 3]$ .
In the fifth test, there is only one element, therefore no operations are needed.
In the second test, you can apply one operation with $k=1$ and $l=1$ , set $a_1 := a_2$ , and the array becomes $[1, 1]$ with $1$ operation.
In the third test, you can apply one operation with $k=1$ and $l=4$ , set $a_4 := a_5$ , and the array becomes $[4, 4, 4, 4, 4]$ .
In the fourth test, you can apply one operation with $k=1$ and $l=3$ , set $a_3 := a_4$ , and the array becomes $[4, 2, 3, 3]$ , then you can apply another operation with $k=2$ and $l=1$ , set $a_1 := a_3$ , $a_2 := a_4$ , and the array becomes $[3, 3, 3, 3]$ .
In the fifth test, there is only one element, therefore no operations are needed.
C++ 编辑器
输入
输出
可保存默认模板；新题优先使用已保存模板。
当前快捷键仅展示，暂不支持修改。
- 撤销
Ctrl / ⌘ + Z - 重做
Ctrl / ⌘ + Y - 查找
Ctrl / ⌘ + F - 全选
Ctrl / ⌘ + A - 复制
Ctrl / ⌘ + C - 剪切
Ctrl / ⌘ + X - 粘贴
Ctrl / ⌘ + V - 自动排版
工具栏排版按钮 - 草稿保存
编辑时自动保存到本机
历史
提交记录
状态说明时间源码
AI
作答助手
你好，我是作答助手。可以问思路、复杂度、样例含义或代码报错原因；不会直接给出完整 AC 代码。
确定要清空代码吗？
提交通过
评测结果：Accepted