UVa1451 数形结合

来源：互联网发布：阿里云北京机房编辑：程序博客网时间：2024/06/07 00:09

//#include<bits/stdc++.h>#include<stdio.h>#include<algorithm>#include<queue>#include<string.h>#include<iostream>#include<math.h>#include<set>#include<map>#include<vector>#include<iomanip>using namespace std;#define ll long long#define pb push_backconst int maxn=2e5+9;char s[maxn];int sum[maxn];int Q[maxn];int cmp(int x1,int x2,int x3,int x4){//比较x1-x2 ,x3-x4的斜率return (sum[x2]-sum[x1])*(x4-x3)-(sum[x4]-sum[x3])*(x2-x1);}int main(){int T;scanf("%d",&T);while(T--){int n,len;scanf("%d%d%s",&n,&len,s+1);sum[0]=0;for(int i=1;i<=n;i++)sum[i]=sum[i-1]+s[i]-'0';int ansl=0,ansr=len;//ansl不要int l=0,r=0;for(int i=len;i<=n;i++){while(r-l>1 && cmp(Q[r-1],i-len,Q[r-2],i-len)<0)r--;//删上凸点Q[r++]=i-len;while(r-l>1 && cmp(Q[l+1],i,Q[l],i)>=0)l++;//l+1斜率更大//l寻找切点int tt=cmp(Q[l],i,ansl,ansr);if(tt>0 || tt==0&&(i-Q[l]<ansr-ansl))ansr=i,ansl=Q[l];}printf("%d %d\n",ansl+1,ansr);}}

细节都在注释里了

相关的论文暂时不会去看，等到学计算几何的时候集中攻略吧

阅读全文

0 0