我有一个包含 7 个元素的变量,我需要随机选择 3 个元素,但这里是我希望它避免的特定 3 个元素组合。我该如何编码? (例如,我需要它来避免组合 [2,5,7] 和 [1,3,6])
这是我目前所拥有的:
var Allregions = [
'1',
'2',
'3',
'4',
'5',
'6',
'7']
var ShowRegions = [];
do {
ShowRegions [ShowRegions.length] = Allregions.splice(
Math.floor(Math.random() * Allregions.length)
, 1)[0];
} while (ShowRegions.length < 3);
编辑:我想澄清一些事情:“数字”只是占位符,因为它们实际上是从代码的不同部分调用元素。即 1 实际上类似于“页面横幅”。因此,我编写的代码可以很好地选择 3 个独特元素来填充网页,但它不允许我控制(不)显示哪 3 个元素组合。
最佳答案
此函数将返回一个没有重复字母序列且没有排除项的随机数。
var allRegions = ['1', '2', '3', '4', '5', '6', '7'];
// to skip sequence of repeated letters.
var isSequence = /^([a-zA-Z0-9])\1+$/;
// to skip, if the combination has duplicates.
var hasDuplicates = /([a-zA-Z0-9]).*?\1/;
function isNotUniqueCombination(ex, rand) {
for (var n = 0; n < ex.length; n++) {
var e = ex[n];
var combinations = [
[e[0], e[1], e[2]],
[e[0], e[2], e[1]],
[e[1], e[0], e[2]],
[e[1], e[2], e[0]],
[e[2], e[0], e[1]],
[e[2], e[1], e[0]]
];
for (var i = 0; i < combinations.length; i++) {
var com = combinations[i];
if (com.join("") === rand.join("")) return true;
}
}
return false;
}
/**
* Return a random number without sequence of repeated letters & without excludes
* @param {String} array
* @param {String} excludes
*/
function getRandom(array, excludes) {
// Random number array
var randomNumber = [];
var excludesMap = excludes.map(function(e) {
return e.join("");
});
do {
// Generate random number
randomNumber = [
array[Math.floor(Math.random() * array.length)],
array[Math.floor(Math.random() * array.length)],
array[Math.floor(Math.random() * array.length)]
];
} while (excludesMap.indexOf(randomNumber.join("")) !== -1 || isSequence.test(randomNumber.join("")) || hasDuplicates.test(randomNumber.join("")) || isNotUniqueCombination(excludes, randomNumber));
return randomNumber;
}
var excludes = [
['2', '5', '7'],
['1', '3', '6']
];
// Test Case
// =========
for (var i = 0; i < 1e3; i++) {
var arr = getRandom(allRegions, excludes);
var div = document.createElement('div');
div.innerHTML = arr.join("");
document.body.appendChild(div);
// Check if the string contains a sequence of repeated letters of has duplicates
if (isSequence.test(arr.join("")) || hasDuplicates.test(arr.join("")) || isNotUniqueCombination(excludes, arr)) {
div.style.color = "#ff0000";
div.innerHTML += " [ sequence of repeated letters found || duplicates found ]";
document.body.appendChild(div);
break;
}
}
// ===
关于javascript - 如何使用 rand 和 split 函数避免特定的 3 元素组合?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/46979058/