poj 1118

<div class="plm" style="text-align: center; font-size: 12pt; color: rgb(34, 34, 34); clear: both;"><div class="ptt" id="problem_title" style="font-size: 18pt; font-weight: bold; color: blue; padding: 10px;"><span style="color: green;">B - </span>Lining Up</div><span id="crawlSuccess" class="crawlInfo" style="display: inline;"><strong>Time Limit:</strong><span id="timeLimit">2000</span>MS     <strong>Memory Limit:</strong><span id="memoryLimit">32768</span>KB     <strong>64bit IO Format:</strong><span id="_64IOFormat">%I64d & %I64u</span></span><div id="problem_opt" style="font-size: 12px; margin-top: 10px;"><a target=_blank id="submit" class="ui-button ui-widget ui-state-default ui-corner-all ui-button-text-only" role="button" style="display: inline-block; position: relative; padding: 0px; margin-right: 0.1em; cursor: pointer; vertical-align: middle; overflow: visible; font-family: Verdana, Arial, sans-serif; font-size: 1em; border: 1px solid rgb(211, 211, 211); color: rgb(85, 85, 85); border-radius: 4px; background: url(http://acm.hust.edu.cn/vjudge/jquery-ui-1.11.1.custom/images/ui-bg_glass_75_e3e4f8_1x400.png) 50% 50% repeat-x rgb(227, 228, 248);"><span class="ui-button-text" style="display: block; padding: 0.4em 1em;">Submit</span></a> <a target=_blank id="problem_status" href="http://acm.hust.edu.cn/vjudge/contest/view.action?cid=87169#status//B/0" class="ui-button ui-widget ui-state-default ui-corner-all ui-button-text-only" role="button" style="display: inline-block; position: relative; padding: 0px; margin-right: 0.1em; cursor: pointer; vertical-align: middle; overflow: visible; text-decoration: none; font-family: Verdana, Arial, sans-serif; font-size: 1em; border: 1px solid rgb(211, 211, 211); color: rgb(85, 85, 85); border-radius: 4px; background: url(http://acm.hust.edu.cn/vjudge/jquery-ui-1.11.1.custom/images/ui-bg_glass_75_e3e4f8_1x400.png) 50% 50% repeat-x rgb(227, 228, 248);"><span class="ui-button-text" style="display: block; padding: 0.4em 1em;">Status</span></a> <a target=_blank id="problem_practice" target="_blank" href="http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=16557" class="ui-button ui-widget ui-state-default ui-corner-all ui-button-text-only" role="button" style="display: inline-block; position: relative; padding: 0px; margin-right: 0.1em; cursor: pointer; vertical-align: middle; overflow: visible; text-decoration: none; font-family: Verdana, Arial, sans-serif; font-size: 1em; border: 1px solid rgb(211, 211, 211); color: rgb(85, 85, 85); border-radius: 4px; background: url(http://acm.hust.edu.cn/vjudge/jquery-ui-1.11.1.custom/images/ui-bg_glass_75_e3e4f8_1x400.png) 50% 50% repeat-x rgb(227, 228, 248);"><span class="ui-button-text" style="display: block; padding: 0.4em 1em;">Practice</span></a> <a target=_blank id="problem_origin" target="_blank" href="http://acm.hust.edu.cn/vjudge/problem/visitOriginUrl.action?id=16557" class="ui-button ui-widget ui-state-default ui-corner-all ui-button-text-only" role="button" style="display: inline-block; position: relative; padding: 0px; margin-right: 0.1em; cursor: pointer; vertical-align: middle; overflow: visible; text-decoration: none; font-family: Verdana, Arial, sans-serif; font-size: 1em; border: 1px solid rgb(211, 211, 211); color: rgb(85, 85, 85); border-radius: 4px; background: url(http://acm.hust.edu.cn/vjudge/jquery-ui-1.11.1.custom/images/ui-bg_glass_75_e3e4f8_1x400.png) 50% 50% repeat-x rgb(227, 228, 248);"><span class="ui-button-text" style="display: block; padding: 0.4em 1em;">POJ 1118</span></a></div></div><div style="color: rgb(34, 34, 34); font-family: Verdana, Arial, sans-serif; font-size: 14px; width: 960px; margin: auto;"><div class="hiddable" id="vj_description" style="font-family: 'times new roman'; font-size: 17px;"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Description</p><div class="textBG" style="border-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px; background-color: rgb(234, 235, 255);"><div class="ptx" lang="en-US" style="font-family: 'Times New Roman', Times, serif; font-size: 12pt;">"How am I ever going to solve this problem?" said the pilot. Indeed, the pilot was not facing an easy task. She had to drop packages at specific points scattered in a dangerous area. Furthermore, the pilot could only fly over the area once in a straight line, and she had to fly over as many points as possible. All points were given by means of integer coordinates in a two-dimensional space. The pilot wanted to know the largest number of points from the given set that all lie on one line. Can you write a program that calculates this number? Your program has to be efficient! </div></div></div><div class="hiddable" id="vj_input" style="font-family: 'times new roman'; font-size: 17px;"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Input</p><div class="textBG" style="border-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px; background-color: rgb(234, 235, 255);"><div class="ptx" lang="en-US" style="font-family: 'Times New Roman', Times, serif; font-size: 12pt;">Input consist several case,First line of the each case is an integer N ( 1 < N < 700 ),then follow N pairs of integers. Each pair of integers is separated by one blank and ended by a new-line character. The input ended by N=0.</div></div></div><div class="hiddable" id="vj_output" style="font-family: 'times new roman'; font-size: 17px;"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Output</p><div class="textBG" style="border-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px; background-color: rgb(234, 235, 255);"><div class="ptx" lang="en-US" style="font-family: 'Times New Roman', Times, serif; font-size: 12pt;">output one integer for each input case ,representing the largest number of points that all lie on one line.</div></div></div><div class="hiddable" id="vj_sampleInput" style="font-family: 'times new roman'; font-size: 17px;"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Sample Input</p><div class="textBG" style="border-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px; background-color: rgb(234, 235, 255);"><pre class="sio" style="white-space: pre-wrap; word-wrap: break-word; font-family: 'Courier New', Courier, monospace; font-size: 12pt;">51 12 23 39 1010 110

Sample Output

3

#include <stdio.h>#include <algorithm>#define inf 9999999using namespace std; struct point{int x;int y;};int main(){int n, i, j;point p[710];double k[710];while(scanf("%d", &n), n){int max = 0;for(i = 1;i <= n;i++)scanf("%d%d", &p[i].x, &p[i].y);for(i = 1;i <= n;i++){int count = 0;for(j = 1;j <= n;j++){if(i==j) continue;if(p[i].x==p[j].x)k[count++] = inf;elsek[count++] = (double)(1.0 *p[j].y - p[i].y) / (p[j].x - p[i].x);}sort(k,k+count);int now = 1;for(j = 1;j < n;j++){if(k[j]==k[j-1]) now++; else { if(now > max) max = now; now = 1; }}}printf("%d\n",max+1);}}