【dp】51nod 1270 陣列的最大代價

只有最底端和最頂端兩條路是可能最優的。

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
//#pragma comment(linker, "/STACK:102400000,102400000")

const double PI = acos(-1.0);
const double eps = 1e-6;
const int INF=0x3f3f3f3f;
const LL mod = 1e9+7;
const int N = 50000+10;
const int M = 2500000;

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