uva 10585 - Center of symmetry（水）

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题目链接：uva 10585 - Center of symmetry

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;typedef long long ll;struct Point {ll x, y;void read() { scanf("%lld%lld", &x, &y); }bool operator < (const Point& u) const { return x < u.x || (x == u.x && y < u.y); };Point (ll x = 0, ll y = 0): x(x), y(y) {}Point operator + (const Point& u) { return Point(x+u.x,y+u.y); }Point operator - (const Point& u) { return Point(x-u.x,y-u.y); }ll operator * (const Point& u) { return x*u.y - y*u.x; }};const int maxn = 10005;int N;Point A[maxn];ll dis(Point u) {return u.x*u.x + u.y*u.y;}bool judge () {ll x = A[0].x + A[N-1].x;ll y = A[0].y + A[N-1].y;for (int i = 1; i < N/2; i++) {int j = N - i - 1;if (A[i].x + A[j].x != x || A[i].y + A[j].y != y)return false;}return true;}int main () {int cas;scanf("%d", &cas);while (cas--) {scanf("%d", &N);for (int i = 0; i < N; i++)A[i].read();sort(A, A + N);printf("%s\n", judge() ? "yes" : "no");}return 0;}

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