HDU 1115 Lifting the Stone

来源：互联网发布：面试php基础知识编辑：程序博客网时间：2024/06/04 07:35

PS: 几何基础，求解多边形重心问题。

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <vector>#include <cmath>using namespace std;struct point{    double x, y;    point(double x=0, double y=0):x(x), y(y) {}};point operator - (point A, point B) {    return point(A.x-B.x, A.y-B.y);}double Cross(point A, point B) {    return A.x*B.y - A.y*B.x;}vector<point> v;int n;int main() {    int T;    point tmp;    scanf("%d", &T);    while(T--) {        scanf("%d", &n);        v.clear();        for(int i = 0; i < n; i++) {            scanf("%lf%lf", &tmp.x, &tmp.y);            v.push_back(tmp);        }        point res;        res.x = 0, res.y = 0;        double sum = 0, det;        for(int i = 1; i < n-1; i++) {            det = Cross(v[i]-v[0], v[i+1]-v[0]);            res.x += det*(v[0].x+v[i].x+v[i+1].x);            res.y += det*(v[0].y+v[i].y+v[i+1].y);            sum += det;        }        res.x = res.x/(sum*3);        res.y = res.y/(sum*3);        printf("%.2f %.2f\n", res.x, res.y); // G++， C++     }    return 0;}

0 0