poj2187 the farthest point of plane, Garham_scan algorithm to find convex packet

poj2187 the farthest point of the plane, Garham_scan algorithm to find convex hull beauty Contest

Time Limit: 3000MS		Memory Limit: 65536K
Total Submissions: 29666		Accepted: 9180

Description

Bessie, Farmer John's Prize cow, had just won first place in a bovine beauty contest, earning the title ' Miss Cow World '. As a result, Bessie would make a tour of N (2 <= n <= 50,000) farms around the world in order to spread goodwill BETW Een farmers and their cows. For simplicity, the world would be represented as a two-dimensional plane, where each farm was located at a pair of integers Coordinates (x, y), each has a value in the range-10,000 ... No. Farms share the same pair of coordinates.

Even though Bessie travels directly in a straight line between pairs of farms, the distance between some farms can be quit e large, so she wants-bring a suitcase full of hay with her so she she had enough food to eat on each leg of her journey. Since Bessie refills her suitcase at every farm she visits, she wants to determine the maximum possible distance she might Need to travel so she knows the size of suitcase she must bring. Help Bessie by computing the maximum distance among all pairs of farms.

Input

* Line 1: A single integer, N

* Lines 2..n+1:two space-separated integers x and y specifying coordinate of each farm

Output

* Line 1: A single integer, which is the squared distance between the pair of farms, is farthest apart from each other.

Sample Input

40 00 11) 11 0

Sample Output

2

Hint

Farm 1 (0, 0) and Farm 3 (1, 1) have the longest distance (square root of 2) test instructions: The farthest point of the plane to the idea: the first convex hull, in the point of the convex polygon of violence to solve the answer, slot point: Double super , int is only over.

#include <iostream>#include<cstdio>#include<cstdlib>#include<cstring>#include<algorithm>#include<math.h>#include<ctype.h>using namespacestd;Const intmaxn=1000100;Const intInf= (1<< -);Const inteps=0.00000001;intN;structpoint{intx, y; Friendint operator*(Point A,point B) {returna.x*b.y-a.y*b.x; } Friend Pointoperator-(Point A,point B) {return{a.x-b.x,a.y-B.Y}; }}; Point FARM[MAXN]; Point ANS_FARM[MAXN];intAns_top;intDist2 (Point a,point B) {inttx=a.x-b.x,ty=a.y-b.y; returntx*tx+ty*Ty;}BOOLCmpyx (ConstPoint A,ConstPoint B) {    if(A.Y&LT;B.Y)return true; if(a.y==b.y) {        returna.x<=b.x; }    return false;}BOOLcmpConstPoint A,ConstPoint B) {    intTmp= (a-farm[0]) * (b-farm[0]); returnTmp>0;}voidGraham_scan () {sort (farm,farm+N,cmpyx); Sort (Farm+1, farm+n,cmp); Ans_top=0; Ans_farm[ans_top++]=farm[0]; Ans_farm[ans_top++]=farm[1];  for(intI=2; i<n;i++){        if((ans_farm[ans_top-1]-ans_farm[ans_top-2]) * (farm[i]-ans_farm[ans_top-1]) <0) {Ans_top--; Ans_farm[ans_top++]=Farm[i]; }        Elseans_farm[ans_top++]=Farm[i]; }}intMain () { while(cin>>N) {         for(intI=0; i<n;i++) {scanf ("%d%d",& (farm[i].x),&(FARM[I].Y));        } graham_scan (); intans=0;  for(intI=0; i<ans_top-1; i++){             for(intj=i+1; j<ans_top;j++){                inttmp=Dist2 (Ans_farm[i],ans_farm[j]); if(Tmp>ans) ans=tmp; }} printf ("%d\n",(int) ans); }    return 0;}

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poj2187 the farthest point of plane, Garham_scan algorithm to find convex packet