Problem Address：http://acm.zjut.edu.cn/ShowProblem.aspx?ShowID=1051
简单题。
捡了一个公式：
S△=1/2 * |(x2-x1)(y3-y1)-(x3-x1)(y2-y1)|
贴代码：
#include <iostream>#include <cmath>using namespace std;int main(){ int x1,y1,x2,y2,x3,y3; scanf("%d %d %d %d", &x1, &y1, &x2, &y2); double d2=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)); double d=0.0,h; while(scanf("%d %d", &x3, &y3)!=EOF) { h = (x2-x1)*(y3-y1)-(x3-x1)*(y2-y1); if (h<0) h = -h; h = double(h)/ (double)d2; if (h>d) d=h; } printf("%.3f/n", d); return 0;}
