The Monty Hall Problem 蒙提霍尔问题验证

the-monty-hall-problem.js

// The Monty Hall problem
// 蒙提霍尔问题
var posibilities = [
	['C', 'A', 'B'],
	['C', 'B', 'A'],
	['B', 'C', 'A'],
	['B', 'A', 'C'],
	['A', 'B', 'C'],
	['A', 'C', 'B'],
];// Apple, Banana, Car

function lucky(n) {
	var c = [0, 0]; // [original-choice, another]
	for(var j=0; j<n; j++) {
		var picked = Math.floor(Math.random() * 3); // random original-choice 原选择随机
		var i = Math.floor(Math.random() * 6); // random situation 场景随机
		var t = posibilities[i].slice();

		// opened by Monty Hall
		var k = (picked+1)%3;
		if(t[k] != 'C') {
			t.splice(k, 1);
			if(k<picked) picked--;
		} else {
			k = (picked+2)%3;
			if(t[k] != 'C') {
				t.splice(k, 1);
				if(k<picked) picked--;
			}
		}
		// count lucky 幸运计数
		if(t[picked] == 'C') { // original choice is Car 保持原来的选择中奖次数
			c[0]++;
		} else if(t[1-picked] == 'C') { // switch to another got Car 改选另外一个中奖次数
			c[1]++;
		}
	}
	return {"original-choice": c[0]/n, "change-to-another": c[1]/n};
}

// print result 打印结果
console.log(lucky(10000));
// 结果示例 {original-choice: 0.3386, change-to-another: 0.6614}