Codeforces 484D-kindergarten

最新推荐文章于 2020-08-01 07:34:49 发布

Wang_128

最新推荐文章于 2020-08-01 07:34:49 发布

阅读量415

点赞数

CC 4.0 BY-SA版权

分类专栏： Codeforces ----线性dp

本文链接：https://blog.youkuaiyun.com/a664607530/article/details/51456810

Codeforces 同时被 2 个专栏收录

140 篇文章

订阅专栏

----线性dp

66 篇文章

订阅专栏

本文探讨了一个幼儿园孩子分组的问题，旨在通过算法找到一种分组方式，使得每组孩子的最大魅力值差达到整体最大值。文章提供了一段实现该目标的C++代码。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

In a kindergarten, the children are being divided into groups. The teacher put the children in a line and associated each child with his or her integer charisma value. Each child should go to exactly one group. Each group should be a nonempty segment of consecutive children of a line. A group's sociability is the maximum difference of charisma of two children in the group (in particular, if the group consists of one child, its sociability equals a zero).

The teacher wants to divide the children into some number of groups in such way that the total sociability of the groups is maximum. Help him find this value.

Input

The first line contains integer n — the number of children in the line (1 ≤ n ≤ 106).

The second line contains n integers ai — the charisma of the i-th child ( - 109 ≤ ai ≤ 109).

Output

Print the maximum possible total sociability of all groups.

Examples

input
5
1 2 3 1 2

output
3

input
3
3 3 3

output
0

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

const int maxn = 1e6+5;

int n, a[maxn];
long long int dp[maxn][2];

int main ()
{
    scanf("%d%d",&n,&a[1]);
    for (int i=2;i<=n;i++)
    {
        scanf("%d",&a[i]);
        if(a[i]>a[i-1])
        {
            dp[i][0]=max(dp[i-1][1],dp[i-1][0]+a[i]-a[i-1]);
            dp[i][1]=max(dp[i-1][1],dp[i-1][0]);
        }
        else
        {
            dp[i][1]=max(dp[i-1][0],dp[i-1][1]+a[i-1]-a[i]);
            dp[i][0]=max(dp[i-1][0],dp[i-1][1]);
        }
    }
    printf("%lld\n", max(dp[n][0], dp[n][1]));
    return 0;
}