https://www.luogu.org/problemnew/show/P2376
看了题解做的，根本不会贪心。。
1 #include<cstdio> 2 #include<algorithm> 3 #include<cstring> 4 #include<vector> 5 using namespace std; 6 #define fi first 7 #define se second 8 #define mp make_pair 9 #define pb push_back 10 typedef long long ll; 11 typedef unsigned long long ull; 12 typedef pair<int,int> pii; 13 int n,c; 14 int ans; 15 pii t1[1010]; 16 int len; 17 int main() 18 { 19 int t,i,x,y,s; 20 bool fl; 21 scanf("%d%d",&n,&c); 22 for(i=1;i<=n;i++) 23 { 24 scanf("%d%d",&x,&y); 25 if(x>=c) ans+=y; 26 else t1[++len]=mp(x,y); 27 } 28 sort(t1+1,t1+len+1); 29 while(1) 30 { 31 fl=0; 32 for(i=1;i<=len;i++) 33 if(t1[i].se!=0) 34 fl=1; 35 if(!fl) break; 36 s=0; 37 for(i=len;i>=1;i--) 38 { 39 t=min(t1[i].se,(c-s)/t1[i].fi); 40 s+=t1[i].fi*t; 41 t1[i].se-=t; 42 } 43 if(s<c) 44 { 45 fl=0; 46 for(i=1;i<=len;i++) 47 if(t1[i].se!=0) 48 fl=1; 49 if(!fl) break; 50 for(i=1;i<=len;i++) 51 if(t1[i].se) 52 { 53 --t1[i].se; 54 break; 55 } 56 } 57 ans++; 58 } 59 printf("%d",ans); 60 return 0; 61 }