codeforces 24C 找规律

X轴与Y轴独立，且当n为奇数时，循环节为2*n。

#include <bits/stdc++.h>#define aint(x) x.begin(), x.end()using namespace std;typedef long long LL;const int maxn = 111;const int pi = acos(-1.0);struct Point {     int x, y;     Point(int x = 0, int y = 0):x(x),y(y) {};     void getin() {        scanf("%d%d", &x, &y);     }};Point Getpair(Point a, Point b) {    return {2*b.x - a.x, 2*b.y-a.y};}vector<int> X, Y;int main() {    Point s;    vector<Point> V;    int n;    long long m;    scanf("%d%lld", &n, &m);s.getin();    for(int i = 1; i <= n; i++) {        Point tmp;        tmp.getin();        V.push_back(tmp);    }    for(int i = 1; i <= 2; i++)        for(auto it:V) {            s = Getpair(s, it);            X.push_back(s.x);            Y.push_back(s.y);        }    printf("%d %d\n", X[(m-1)%(2*n)], Y[(m-1)%(2*n)]);    return 0;}