poj2318

简单题，二分查找

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
using namespace std;

#define maxn 5005

struct Line
{
    int u, d;
} line[maxn];

int n, m, x1, x2, y1, y2;
int toy[maxn];

bool left(int x, int y, Line a)
{
    if (x < a.d + (y - y2) * (a.u - a.d) * 1.0 / (y1 - y2))
        return true;
    return false;
}

int binarysearch(int x, int y)
{
    int l = 0, r = n;
    int mid;

    while (l < r)
    {
        mid = (l + r) / 2;
        if (left(x, y, line[mid]))
            r = mid;
        else
            l = mid + 1;
    }
    return l;
}

int main()
{
    //freopen("t.txt", "r", stdin);
    while (scanf("%d", &n), n != 0)
    {
        memset(toy, 0, sizeof(toy));
        scanf("%d%d%d%d%d", &m, &x1, &y1, &x2, &y2);
        for (int i = 0; i < n; i++)
            scanf("%d%d", &line[i].u, &line[i].d);
        for (int i = 0; i < m; i++)
        {
            int x, y;
            scanf("%d%d", &x, &y);
            toy[binarysearch(x, y)]++;
        }
        for (int i = 0; i <= n; i++)
            printf("%d: %d\n", i, toy[i]);
        printf("\n");
    }
    return 0;
}