A13148. Domino for Young
编程题
普及/提高-
知识点
题目描述
You are given a Young diagram.
Given diagram is a histogram with $n$ columns of lengths $a_1, a_2, \ldots, a_n$ ( $a_1 \geq a_2 \geq \ldots \geq a_n \geq 1$ ).
Young diagram for $a=[3,2,2,2,1]$ .Your goal is to find the largest number of non-overlapping dominos that you can draw inside of this histogram, a domino is a $1 \times 2$ or $2 \times 1$ rectangle.
Given diagram is a histogram with $n$ columns of lengths $a_1, a_2, \ldots, a_n$ ( $a_1 \geq a_2 \geq \ldots \geq a_n \geq 1$ ).
Young diagram for $a=[3,2,2,2,1]$ .Your goal is to find the largest number of non-overlapping dominos that you can draw inside of this histogram, a domino is a $1 \times 2$ or $2 \times 1$ rectangle.
输入格式
The first line of input contain one integer $n$ ( $1 \leq n \leq 300\,000$ ): the number of columns in the given histogram.
The next line of input contains $n$ integers $a_1, a_2, \ldots, a_n$ ( $1 \leq a_i \leq 300\,000, a_i \geq a_{i+1}$ ): the lengths of columns.
The next line of input contains $n$ integers $a_1, a_2, \ldots, a_n$ ( $1 \leq a_i \leq 300\,000, a_i \geq a_{i+1}$ ): the lengths of columns.
输出格式
Output one integer: the largest number of non-overlapping dominos that you can draw inside of the given Young diagram.
输入输出样例
输入 #1
5 3 2 2 2 1
输出 #1
4
说明/提示
Some of the possible solutions for the example:
