【dp】 codeforces 455A Boredom

简单DP。。。注意long long。。

#include <iostream>  
#include <queue>  
#include <stack>  
#include <map>  
#include <set>  
#include <bitset>  
#include <cstdio>  
#include <algorithm>  
#include <cstring>  
#include <climits>  
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 100005
#define maxm 100005
#define eps 1e-10
#define mod 3
#define INF 1e17
#define lowbit(x) (x&(-x))  
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid  
#define rson o<<1 | 1, mid+1, R  
typedef long long LL;
//typedef int LL;
using namespace std;

LL dp[2][maxn];
int c[maxn];
int main(void)
{
	int n, x;
	scanf("%d", &n);
	for(int i = 1; i <= n; i++) {
		scanf("%d", &x);
		c[x]++;
	}
	for(int i = 100000; i >= 1; i--) {
		dp[1][i] = max(dp[1][i+2], dp[0][i+2]) + (LL)c[i]*i;
		dp[0][i] = max(dp[0][i+1], dp[1][i+1]);
	}
	printf("%I64d\n", max(dp[1][1], dp[0][1]));
	return 0;
}