poj2181

简单dp

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
using namespace std;

int n, even, odd;

int main()
{
// freopen("t.txt", "r", stdin);
scanf("%d", &n);
if (n == 1)
{
int a;
scanf("%d", &a);
printf("%d\n", a);
return 0;
}
scanf("%d%d", &odd, &even);
int a, temp;
temp = even;
even = odd - even;
odd = max(temp, odd);
for (int i = 2; i < n; i++)
{
scanf("%d", &a);
temp = max(odd, even + a);
even = max(even, odd - a);
odd = temp;
}
printf("%d\n", max(even, odd));
return 0;
}