POJ2398【判断点在直线哪一侧+二分查找区间】

题意：同POJ2318

#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<cstring>
using namespace std;
struct point {
    int x, y;
};
struct Node {
    point Low, High;
}line[5010];
int Num[5010];
int par[5010];
bool cmp(Node A, Node B) {
    return A.High.x < B.High.x;
}
bool is_right(int x, int y, Node ln) {
    point P = ln.High;
    point Q = ln.Low;
    if (((P.x - x)*(Q.y - y) - (P.y - y)*(Q.x - x)) > 0)
        return true;
    else
        return false;
}
void bin_seach(int x, int y, int n) {
    int left = 1;
    int right = n;
    while (left <= right) {
        int mid = (left + right) / 2;
        if (is_right(x, y, line[mid])) {
            left = mid + 1;
        }
        else {
            right = mid - 1;
        }
    }
    par[left]++;
}
int main() {
    int n, m, i, j, x1, x2, y1, y2;
    while (scanf("%d", &n), n) {
        memset(par, 0, sizeof(par));
        memset(Num, 0, sizeof(Num));
        scanf("%d%d%d%d%d", &m, &x1, &y1, &x2, &y2);
        for (int i = 1; i <= n; i++) {
            scanf("%d", &line[i].High.x);
            line[i].High.y = y1;
            scanf("%d", &line[i].Low.x);
            line[i].Low.y = y2;
        }
        sort(line + 1, line + 1 + n, cmp);
        int xx, yy;
        int t = m;
        while (m--) {
            scanf("%d%d", &xx, &yy);
            bin_seach(xx, yy, n);
        }
        for (int i = 1; i <= n + 1; i++) {
            if (par[i])
                Num[par[i]]++;
        }
        printf("Box\n");
        for (int i = 1; i <= t; i++) {
            if (Num[i])
                printf("%d: %d\n", i, Num[i]);
        }
    }
    return 0;
}