CodeForces 166B（凸包）

判断一下A所构成的凸包是不是跟总的凸包一样就可以了..

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <queue>
#include <vector>
#include <set>

using namespace std;

const int INF = ~0U >> 1;
const int maxn = 200000 + 7;
const int mod = 1000000000 + 7;
const double eps = 1e-6;
typedef long long LL;

struct point {
    double x, y;
//    bool operator<(const point &rhs) const {
//        if(x != rhs.x) return x < rhs.x;
//        return y < rhs.y;
//    }
    bool operator==(const point &rhs) const {
        if(fabs(x - rhs.x) < eps || fabs(y - rhs.y) < eps) return true;
        return false;
    }
    bool operator!=(const point &rhs) const {
        if(fabs(x - rhs.x) > eps || fabs(y - rhs.y) > eps) return true;
        return false;
    }
};

bool mult(point sp, point ep, point op) {
    return (sp.x - op.x) * (ep.y - op.y) > (ep.x - op.x) * (sp.y - op.y);
}

bool operator < (const point &l, const point &r) {
    return l.y < r.y || (l.y == r.y && l.x < r.x);
}

int graham(point pnt[], int n, point res[]) {
    int i, len, k = 0, top = 1;
    sort(pnt, pnt + n);
    if (n == 0) return 0;
    res[0] = pnt[0];
    if (n == 1) return 1;
    res[1] = pnt[1];
    if (n == 2) return 2;
    res[2] = pnt[2];
    for (i = 2; i < n; i++) {
        while (top && mult(pnt[i], res[top], res[top-1])) top--;
        res[++top] = pnt[i];
    }
    len = top;
    res[++top] = pnt[n - 2];
    for (i = n - 3; i >= 0; i--) {
        while (top!=len && mult(pnt[i], res[top],res[top-1])) top--;
        res[++top] = pnt[i];
    }
    return top;
}

int n, m;
point a[maxn];
point ans1[maxn], ans2[maxn];

set<point> s;

int main() {
    scanf("%d", &n);
    for(int i = 0; i < n; ++i) {
        scanf("%lf%lf", &a[i].x, &a[i].y);
        s.insert(a[i]);
    }
    int res1 = graham(a, n, ans1);
    scanf("%d", &m);
    bool ok = false;
    for(int i = 0; i < m; ++i) {
        scanf("%lf%lf", &a[i+n].x, &a[i+n].y);
        if(s.count(a[i+n])) {
            ok = true;
//            cout << i << "====" << endl;
        }
    }
    if(ok) {
        printf("NO\n");
        return 0;
    }
//    cout << "==" << endl;
    int res2 = graham(a, n + m, ans2);
    if(res1 != res2) {
        printf("NO\n");
        return 0;
    }
    for(int i = 0; i < res1; ++i) {
        if(ans1[i] != ans2[i]) {
            printf("NO\n");
            return 0;
        }
    }
    printf("YES\n");
    return 0;
}