478. Generate Random Point in a Circle | 478. 在圆内随机生成点（Java）

迷南。 2022-09-10 07:14 149阅读 0赞

## 题目 ##

[https://leetcode.com/problems/generate-random-point-in-a-circle/][https_leetcode.com_problems_generate-random-point-in-a-circle]  
![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16]

## 题解 ##

class Solution { 
        double r, x, y, xMin, xMax, yMin, yMax;
        Random rand;
    
        public Solution(double r, double x, double y) { 
            rand = new Random();
            this.r = r;
            this.x = x;
            this.y = y;
            xMin = x - r;
            xMax = x + r;
            yMin = y - r;
            yMax = y + r;
        }
    
        public double[] randPoint() { 
            double x0 = xMin + (xMax - xMin) * rand.nextDouble();
            double y0 = yMin + (yMax - yMin) * rand.nextDouble();
            while (Math.pow(x0 - x, 2) + Math.pow(y0 - y, 2) > Math.pow(r, 2)) { 
                x0 = xMin + (xMax - xMin) * rand.nextDouble();
                y0 = yMin + (yMax - yMin) * rand.nextDouble();
            }
            return new double[]{ x0, y0};
        }
    }
    
    /** * Your Solution object will be instantiated and called as such: * Solution obj = new Solution(radius, x_center, y_center); * double[] param_1 = obj.randPoint(); */

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]

## 拓展：用概率求圆周率 ##

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 2]

[https_leetcode.com_problems_generate-random-point-in-a-circle]: https://leetcode.com/problems/generate-random-point-in-a-circle/
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220829/d6c6c1e4087b4a42aeb1deee8f98b62c.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]: /images/20220829/97983c709d63431bbf5a7d3daf981f11.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 2]: /images/20220829/c408b3b41bbf4854a5e08c929cac3ec9.png