题意：求一条线上最多几个点

思路：枚举一个点，然后求出过这个点的直线的斜率来求最大值

#include 
  
   
#include 
   
     #include 
    
      #include 
     
       #include 
      
        #include 
       
         using namespace std; const int MAXN = 710; const int INF = 1e7; int arr[MAXN][2],n; float brr[MAXN]; int main() { while (scanf("%d", &n) != EOF && n) { for (int i = 0; i < n; i++) scanf("%d%d", &arr[i][0], &arr[i][1]); int Max = 2; int cnt,num; for (int i = 0; i < n; i++) { cnt = 0; num = 2; for (int j = i+1; j < n; j++) { if (arr[i][0] == arr[j][0]) brr[cnt++] = INF; else brr[cnt++] = fabs((float)(arr[j][1]-arr[i][1])/(float)(arr[j][0]-arr[i][0])); } brr[cnt] = -1; sort(brr, brr+cnt); for (int i = 1; i <= cnt; i++) { if (brr[i] == brr[i-1]) num++; else num = 2; if (num > Max) Max = num; } } printf("%d\n", Max); } return 0; }