pku 1054 二分

 

#include <iostream>
#include <algorithm>
using namespace std;

int n, m, t;

class Point
{
public:
    int x, y;

    bool operator<(const Point &b)
    {
        if (x == b.x)
        {
            return y < b.y;
        }
        else
        {
            return x < b.x;
        }
    }
} point[5010];

bool search(Point a)
{
    int low = 0, high = t;
    while (low <= high)
    {
        int mid = (low + high) / 2;
        if (point[mid] < a)
        {
            low = mid + 1;
        }
        else if (a < point[mid])
        {
            high = mid - 1;
        }
        else
        {
            return true;
        }
    }
    return false;
}

int solve()
{
    int max = 0;
    int i, j;
    for (i = 0; i < t; ++i)
    {
        for (j = i + 1; j < t; ++j)
        {
            int temp = 2;
            Point fx, fy, jump, next;
            fx = point[i];
            fy = point[j];
            jump.x = point[j].x - point[i].x;
            jump.y = point[j].y - point[i].y;

            if (fx.x - jump.x > 0 && fx.x - jump.x <= n && fx.y - jump.y > 0 && fx.y - jump.y <= m)
            {
                continue;
            }
            else if (fx.x + max * jump.x <= 0 || fx.x + max * jump.x > n || fx.y + max * jump.y <= 0 || fx.y + max * jump.y > m)
            {
                continue;
            }
            next.x = fy.x + jump.x;
            next.y = fy.y + jump.y;
            while (next.x > 0 && next.x <= n && next.y > 0 && next.y <= m)
            {
                if (search(next))
                {
                    temp++;
                    next.x += jump.x;
                    next.y += jump.y;
                }
                else
                {
                    temp = 0;
                    break;
                }
            }
            if (temp > max)
            {
                max = temp;
            }
        }
    }
    return max;
}

int main()
{
    while (scanf("%d %d", &n, &m) != EOF)
    {
        scanf("%d", &t);
        int i;
        for (i = 0; i < t; ++i)
        {
            scanf("%d %d", &point[i].x, &point[i].y);
        }
        sort(point, point + t);
        int temp = solve();
        if (temp > 2)
        {
            printf("%d"n", temp);
        }
        else
        {
            printf("0"n");
        }
    }
    return 0;
}