C:给你一些数,你取了一个数那么比这个数大1,和小1的数字就会被删掉。问你最大能取到的数的和。 先根据数字进行哈希,然后线性的dp一遍,dp[i][1] = ma(dp[i-2][0], dp[i-2][1]) + vis[i]*i,dp[i][0] = max(dp[i-1][0], dp[i-1][1]).1代表取这个数,0代表不取。注意数据类型要用long long。
C. Boredom
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Alex doesn't like boredom. That's why whenever he gets bored, he comes up with games. One long winter evening he came up with a game and decided to play it.
Given a sequence a consisting of n integers. The player can make several steps. In a single step he can choose an element of the sequence (let's denote it ak) and delete it, at that all elements equal to ak?+?1 and ak?-?1 also must be deleted from the sequence. That step brings ak points to the player.
Alex is a perfectionist, so he decided to get as many points as possible. Help him.
Input
The first line contains integer n (1?≤?n?≤?105) that shows how many numbers are in Alex's sequence.
The second line contains n integers a1, a2, ..., an (1?≤?ai?≤?105).
Output
Print a single integer ? the maximum number of points that Alex can earn.
Sample test(s)
input
21 2
output
input
31 2 3
output
input
91 2 1 3 2 2 2 2 3
output
10
Note
Consider the third test example. At first step we need to choose any element equal to 2. After that step our sequence looks like this [2,?2,?2,?2]. Then we do 4 steps, on each step we choose any element equals to 2. In total we earn 10 points.
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