Codeforces 994 C - Two Squares
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思路:
点积叉积应用
代码:
#include<bits/stdc++.h> using namespace std; #define fi first #define se second #define pi acos(-1.0) #define LL long long #define mp make_pair #define pb push_back #define ls rt<<1, l, m #define rs rt<<1|1, m+1, r #define ULL unsigned LL #define pll pair<LL, LL> #define pii pair<int, int> #define piii pair<int,pii> #define mem(a, b) memset(a, b, sizeof(a)) #define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0); #define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout); //head struct P { double x, y; P(){} P(double x, double y):x(x), y(y) {} P operator - (P p) { return P(x-p.x, y-p.y); } double cross(P p) { return x*p.y - y*p.x; } double dot(P p) { return x*p.x + y*p.y; } }; typedef P Vector; bool on_seg(P p, Vector a, Vector b) { if((a-p).cross(b-p) == 0 && (a-p).dot(b-p) <= 0) return true; else return false; } double area2(Vector a, Vector b, Vector c) { return (b-a).cross(c-a); } bool intersect(Vector a, Vector b, Vector c, Vector d) { if(area2(a, c, d) == 0 && area2(b, c, d) == 0 && !on_seg(a, c, d) && !on_seg(b, c, d) || area2(a, c, d) * area2(b, c, d) > 0 || area2(c, a, b) * area2(d, a, b) > 0 ) return false; else return true; } pii a[4], b[4]; int main() { for (int i = 0; i < 4; i++) scanf("%d %d", &a[i].fi, &a[i].se); for (int i = 0; i < 4; i++) scanf("%d %d", &b[i].fi, &b[i].se); for (int i = 0; i < 4; i++) { for (int j = 0; j < 4; j++) { Vector aa(a[i].fi, a[i].se); Vector bb(a[(i+1)%4].fi, a[(i+1)%4].se); Vector c(b[j].fi, b[j].se); Vector d(b[(j+1)%4].fi, b[(j+1)%4].se); if(intersect(aa, bb, c, d)) return 0*puts("YES"); } } for (int i = 0; i < 4; i++) { int x = 0, y = 0, xx = 0, yy = 0; for (int j = 0; j < 4; j++) { Vector A(a[i].fi, a[i].se), B(b[j].fi, b[j].se), C(b[(j+1)%4].fi, b[(j+1)%4].se); if(area2(A, B, C) > 0) x++; else if(area2(A, B, C) < 0)y++; else x++, y++; Vector AA(b[i].fi, b[i].se), BB(a[j].fi, a[j].se), CC(a[(j+1)%4].fi, a[(j+1)%4].se); if(area2(AA, BB, CC) > 0) xx++; else if(area2(AA, BB, CC) < 0) yy++; else xx++, yy++; } if(x == 4 || y == 4 || xx == 4 || yy == 4) return 0*puts("YES"); } puts("NO"); return 0; }
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