【二分】NOIP2011聪明的质检员

进行二分查找即可，我就不多说废话了。

#include<iostream>#include<stdio.h>#include<algorithm>#include<cmath>#include<iomanip>using namespace std;void preprocess(int weight);struct Node{int l,r;};const int SIZE=200005;Node node[SIZE];int n,counter[SIZE],wei[SIZE],value[SIZE];double total[SIZE];int main(){double interval,min_dis,tmp;double standard;int left,right;cin>>n>>interval>>standard;double sum=0;int maximum=-1;for(int i=1;i<=n;i++){scanf("%d%d",&wei[i],&value[i]);maximum=max(wei[i],maximum);sum+=value[i];}min_dis=sum*n;for(int i=1;i<=interval;i++){scanf("%d%d",&node[i].l,&node[i].r);//node[i].l--;  node[i].r--;}left=0; right=maximum;//进行二分查找 while(left<=right){//cout<<"left: "<<left<<" right: "<<right<<endl;int middle=(left+right)/2;//动态规划，O(n)的时间完成预处理 preprocess(middle);tmp=0;for(int i=1;i<=interval;i++){tmp+=(counter[node[i].r]-counter[node[i].l-1])*(total[node[i].r]-total[node[i].l-1]);}//所选的重量越大，检验量就会越大，毫无意义 if(tmp>standard)left=middle+1;else if(tmp<standard)right=middle-1;else if(tmp==standard){min_dis=standard;break;}if(fabs(tmp-standard)<fabs(min_dis-standard))min_dis=tmp;//if((tmp>=standard&&tmp<min_dis)||(tmp<standard&&tmp>min_dis))//min_dis=tmp;//cout<<"middle: "<<middle<<" min_dis "<<min_dis<<endl;}if(min_dis>standard)cout<<fixed<<setprecision(0)<<min_dis-standard<<endl;else cout<<fixed<<setprecision(0)<<standard-min_dis<<endl;//system("pause");return 0;}void preprocess(int weight){counter[0]=0; total[0]=0;if(wei[1]>=weight){counter[1]=1;total[1]=value[1];}else{counter[1]=0;total[1]=0;}for(int i=2;i<=n;i++){if(wei[i]>=weight){counter[i]=counter[i-1]+1;total[i]=total[i-1]+value[i];}else{counter[i]=counter[i-1];total[i]=total[i-1];}}return;}