hdu 5533 Dancing Stars on Me（水）

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题目链接：hdu 5533 Dancing Stars on Me

解题思路

只有n=4时才有可能。

代码

#include <cstdio>#include <cstring>#include <vector>#include <algorithm>using namespace std;const int maxn = 105;struct Point {    int x, y;    Point (int x = 0, int y = 0): x(x), y(y) {}    void read() { scanf("%d%d", &x, &y); }    bool operator == (const Point& u) const { return x == u.x && y == u.y; }    bool operator < (const Point& u) const { return x < u.x || (x == u.x && y < u.y); }    Point operator + (const Point& u) const { return Point(x + u.x, y + u.y); }    int operator * (const Point& u) const { return x * u.x + y * u.y; }    int operator ^ (const Point& u) const { return x * u.y - y * u.x; }};int N;Point P[maxn];bool judge () {    if (N != 4) return false;    vector<int> g;    g.clear();    for (int i = 0; i < N; i++) {        for (int j = i + 1; j < N; j++) {            int x = P[i].x - P[j].x;            int y = P[i].y - P[j].y;            g.push_back(x * x + y * y);        }    }    sort(g.begin(), g.end());    for (int i = 1; i < 4; i++)        if (g[i] != g[0]) return false;    return g[4] == g[5];}int main () {    int cas;    scanf("%d", &cas);    while (cas--) {        scanf("%d", &N);        for (int i = 0; i < N; i++) P[i].read();        printf("%s\n", judge() ? "YES" : "NO");    }    return 0;}

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