D - 买糖果

 1 #include <iostream>

 2 #include <cstdio>

 3 #include <cstdlib>

 4 #include <cstring>

 5 #include <cmath>

 6 using namespace std;

 7 #define FOR(i,a,b) for(int i=a;i<=b;i++)

 8 #define MST(a,b) memset(a,b,sizeof(a))

 9 #define MAXN 105

10 #define MAXM 1050

11 int n,m;

12 int totx,toty,x[MAXN],y[MAXN];

13 int f[2][MAXN][MAXM];

14 int a,b;

15 int main()

16 {

17 

18     while (scanf("%d%d",&n,&m)!=EOF)

19     {

20         FOR(i,1,n)scanf("%d%d",&x[i],&y[i]);

21         scanf("%d%d",&a,&b);

22         MST(f[0],128);

23         totx=0;

24         toty=0;

25         f[0][0][0]=0;

26         FOR(i,1,n)

27         {

28             MST(f[i%2],128);

29             totx+=x[i];

30             FOR(j,0,i)

31             FOR(k,0,totx)

32             {

33                 if(j-1>=0 && k-x[i]>=0 && f[(i+1)%2][j-1][k-x[i]]>=0)f[i%2][j][k]=f[(i+1)%2][j-1][k-x[i]]+y[i];

34                 if(f[(i+1)%2][j][k]>=f[i%2][j][k])f[i%2][j][k]=f[(i+1)%2][j][k];

35             }

36         }

37         int ans=-1;

38         FOR(k,a,totx)

39         if(f[n%2][m][k]>=b && f[n%2][m][k]-b+k-a>ans)ans=f[n%2][m][k]-b+k-a;

40         printf("%d\n",ans);

41     }

42 }