5 1 2 2 3 3 4 4 5 5 6 0
1419HintIn the Sample Input, WANGPENG just follow the given order. He spends 1 second in the first queue, 5 seconds in the 2th queue, 27 seconds in the 3th queue, 169 seconds in the 4th queue, and 1217 seconds in the 5th queue. So the total time is 1419s. WANGPENG has computed all possible orders in his 120-core-parallel head, and decided that this is the optimal choice.
由简单至复杂,先讨论2个的情况:
a1 b1
a2 b2
如果现有的顺序是最佳顺序,那么一定有关系:
a1 + a1*b2 + a2 <= a2 + a2*b1 + a1
等价于 a1*b2 < a2*b1
那么之后的都按照a1*b2 < a2*b1 来排序!
AC代码:
#include <cstdio> #include <cstring> #include <algorithm> using namespace std; const int mo=365*24*60*60; const int maxn=100010; struct fun { __int64 a,b; }node[maxn]; bool cmp(fun a, fun b) { return a.a*b.b<b.a*a.b; } int main() { int n, i, j; while(scanf("%d", &n), n) { for(i = 0; i<n; i++) { scanf("%I64d %I64d", &node[i].a, &node[i].b); } sort(node, node+n, cmp); __int64 ans = 0, tem = 0; for(i = 0; i<n; i++) { ans+=(node[i].a+tem*node[i].b)%mo; ans%=mo; tem = ans; } printf("%I64d\n", ans); } return 0; }
其实我还看了看别人的代码(感觉我的代码逻辑不对劲,但是过了):
a1 b1
a2 b2
如果现有的顺序是最佳顺序,那么一定有关系:
a1 + a1*b2 + a2 <= a2 + a2*b1 + a1
还可以等价于 a1/b1 < a2/b2
这样使得a1和b1在一块了,a2和b2在一块了,对于往后退可以更方便。比如三组:
a1 b1
a2 b2
a3 b3
可以得到 a1/b1 < a2/b2 < a3/b3
以此类推,也可以按照这样排序!
代码(别人的代码,没提交过。。):
#include<iostream> #include<cstdlib> #include<vector> #include<map> #include<cstring> #include<set> #include<string> #include<algorithm> #include<sstream> #include<ctype.h> #include<fstream> #include<string.h> #include<stdio.h> #include<math.h> #include<stack> #include<queue> #include<ctime> //#include<conio.h> using namespace std; const int INF_MAX=0x7FFFFFFF; const int INF_MIN=-(1<<30); const double eps=1e-10; const double pi=acos(-1.0); #define pb push_back //a.pb( ) #define chmin(a,b) ((a)<(b)?(a):(b)) #define chmax(a,b) ((a)>(b)?(a):(b)) template<class T> inline T gcd(T a,T b)//NOTES:gcd( {if(a<0)return gcd(-a,b);if(b<0)return gcd(a,-b);return (b==0)?a:gcd(b,a%b);} template<class T> inline T lcm(T a,T b)//NOTES:lcm( {if(a<0)return lcm(-a,b);if(b<0)return lcm(a,-b);return a*(b/gcd(a,b));} typedef pair<int, int> PII; typedef vector<PII> VPII; typedef vector<int> VI; typedef vector<VI> VVI; typedef long long LL; int dir_4[4][2]={{0,1},{-1,0},{0,-1},{1,0}}; int dir_8[8][2]={{0,1},{-1,1},{-1,0},{-1,-1},{0,-1},{1,-1},{1,0},{1,1}}; //下,左下,左,左上,上,右上,右,右下。 //******* WATER **************************************************************** struct node { LL a, b; double d; bool operator < (const node& k) const{ return a < k.a; //升序 } }; vector<node> vn; LL calc() { LL mod = 365 * 24 * 60 * 60; LL ret = 0; LL sum = 0; for(int i = 0; i < vn.size(); i++) { ret = sum * vn[i].b + vn[i].a; sum += ret; sum %= mod; } return sum; } int main() { int n; node tmp; while(scanf("%d", &n) && n) { vn.clear(); for(int i = 0; i < n; i++) { scanf("%I64d%I64d", &tmp.a, &tmp.b); tmp.d = (double)tmp.a / (tmp.b - 1); vn.push_back(tmp);} //sort(vn.begin(), vn.end()); printf("%I64d\n", calc()); } return 0; }