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法律研究C++ 程序检查给定的一组三个点是否在同一条直线上
这是一个 C++ 程序，用于检查给定的一组三个点是否在同一条直线上。如果这三个点形成的三角形的面积等于零，则这三个点在同一条直线上。
三角形的面积为 −
0.5 * (x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2)).
算法
Begin Generate the points randomly. Calculate the area by using above formula. If area > 0 Then the points don't lie on the straight line. else if area < 0 Then the points don't lie on the straight line. else The points lie on the straight line. End
示例
#include <iostream>
#include <time.h>
#include <stdlib.h>
using namespace std;
static int L = 1;
static int U= 20;
int main(int argc, char **argv) {
int x3, y3, x1, x2, y1, y2;
time_t seconds;
time(&seconds);
srand((unsigned int) seconds);
//Generate the points randomly using rand().
x1 = rand() % ( U- L+ 1) + L;
y1 = rand() % (U - L+ 1) + L;
x2 = rand() % (U - L + 1) + L;
y2 = rand() % (U - L+ 1) + L;
x3 = rand() % (U - L+ 1) + L;
y3 = rand() % (U - L+ 1) + L;
cout << "The points are: (" << x1 << ", " << y1 << "), (" << x2 << ", " << y2 << "), & (" << x3 << ", " << y3 << ")\n";
//calculate area
float a = 0.5 *(x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2));
if (a < 0)
cout << "The points don't lie on the straight line";
else if (a > 0)
cout << "The points don't lie on the straight line ";
else
cout << "The points lie on the straight line";
}输出
The points are: (20, 9), (6, 13), & (13, 11) The points lie on the straight line The points are: (9, 15), (4, 15), & (11, 16) The points don't lie on the straight line
更新于：2019 年 7 月 30 日
669 次浏览
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