cf 456 c

dp 俩种状态。dp[i][0] 表示不取，dp[i][1]表示取

如果i取 那么dp[i][1] = dp[i - 1][0] + s[i]

如果i 不取 dp[i][0] = Max(dp[i -1][0],dp[i - 1][1]

注意数据范围。

#include <cstdio>#include <iostream>#include <cstring>#include <algorithm>using namespace std;typedef __int64 ll;int const MAXN = 100010;ll dp[MAXN][2],s[MAXN];inline ll Max(ll a,ll b){    return a>b?a:b;}int main(){    int n;    scanf("%d",&n);    memset(s,0,sizeof(s));    for(int i = 1;i <= n;i++){        int x;        scanf("%d",&x);        s[x] += x;    }    memset(dp,0,sizeof(dp));    for(int i = 1;i <= 100001;i++){        dp[i][0] = Max(dp[i - 1][1],dp[i - 1][0]);        dp[i][1] = dp[i - 1][0] + s[i];    }    printf("%I64d\n",dp[100001][0]);    return 0;}