HDU 5887 Herbs Gathering

背包，$map$，优化。

和普通背包一样，$map$加一个$erase$优化一下就可以跑的很快了。

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-6;
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
template <class T>
inline void read(T &x)
{
    char c=getchar(); x=0;
    while(!isdigit(c)) c=getchar();
    while(isdigit(c)) {x=x*10+c-'0'; c=getchar();}
}

int n; LL m;
struct X { LL x,y; }s[110];

int main()
{
    while(~scanf("%d%lld",&n,&m))
    {
        map<LL,LL>dp;
        for(int i=1;i<=n;i++) scanf("%lld%lld",&s[i].x,&s[i].y);
     
        dp[0]=0; map<LL,LL>::iterator it;
        for(int i=1;i<=n;i++)
        {
            it=dp.end(); --it;
            for (; ; )
            {
                LL c=it->first, v=it->second;
                if(c+s[i].x<=m) dp[c+s[i].x]=max(dp[c+s[i].x],dp[c]+s[i].y);
                if(it==dp.begin()) break; --it;
            }

            it=dp.begin(); LL mx=0;
            for (; it != dp.end(); )
            {
                if (it->second!=0&&it->second<=mx) dp.erase(it++);
                else { mx=it->second; ++it; }
            }
        }

        LL ans=0;  it=dp.begin();
        for (; it != dp.end(); )
        {
            ans=max(ans,it->second);
            ++it;
        }
        printf("%lld\n",ans);
    }
    return 0;
}