贪心的运用，主要看其比值，取最大值实现贪心...
1 #include<cstdio> 2 #include<algorithm> 3 #include<vector> 4 using namespace std; 5 6 struct room 7 { 8 int j; 9 int f; 10 bool operator < (const room t)const 11 { 12 return (float)j/f >(float)t.j/t.f; 13 } 14 }; 15 16 int main() 17 { 18 //freopen("input.txt","r",stdin); 19 int m,n,i; 20 double ans; 21 while(scanf("%d%d",&m,&n) && (m+1) &&(n+1)) 22 { 23 vector<room> v; 24 room r; 25 ans = 0; 26 for(i = 0; i < n; i++) 27 { 28 scanf("%d%d",&r.j,&r.f); 29 v.push_back(r); 30 } 31 sort(v.begin(),v.end()); 32 33 i = 0; 34 while(m > 0 && i < v.size()) 35 { 36 if(v[i].f <= m) 37 { 38 m -= v[i].f; 39 ans += v[i].j; 40 } 41 else 42 { 43 ans += (double)(v[i].j* m)/v[i].f ; 44 m = 0;//½áÊø 45 } 46 i++; 47 } 48 printf("%.3lf ",ans); 49 } 50 51 return 0; 52 }