从一个数组的大小为N组合 [英] combinations of size N from an array
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问题描述
我想建立一个JavaScript函数从阵列获取的大小为N的所有组合。
可以说,我有:
常量Xarray =19,21,42,23,25,28];
常量N = 4;combinationsOfN(Xarray,N)=>[19,21,42,23]
[19,21,42,25]
[19,21,42,28]
[19,21,23,25]
[19,21,23,28]
[19,21,25,28]
...。 ]
解决方案
自己做,这可能是相当艰难的,因为我已经试过了。目前已经是一个JS的工具,可以实现这个要求, combinations.js
\r
\r\r
\r / **\r
*版权所有2012 AkseliPalén。\r
*创建2012-07-15。\r
*根据MIT许可证授权。\r
* /\r
功能k_combinations(套,K){\r
变种I,J,梳子,头,tailcombs;\r
如果(K> set.length || K&下; = 0){\r
返回[];\r
}\r
如果(K == set.length){\r
返回[设定]\r
}\r
如果(K == 1){\r
梳子= [];\r
对于(i = 0; I< set.length;我++){\r
combs.push([设为[I]);\r
}\r
返回梳子;\r
}\r
梳子= [];\r
对于(i = 0; I< set.length - K + 1;我++){\r
头= set.slice(I,I + 1);\r
tailcombs = k_combinations(set.slice第(i + 1)中,k - 1);\r
为(J = 0; J< tailcombs.length; J ++){\r
combs.push(head.concat(tailcombs [J]));\r
}\r
}\r
返回梳子;\r
}\r
功能组合(套){\r
变种K,I,梳子,k_combs;\r
梳子= [];\r
为(K = 1; K&下; = set.length; k ++){\r
k_combs = k_combinations(套,K);\r
对于(i = 0; I< k_combs.length;我++){\r
combs.push(k_combs [I]);\r
}\r
}\r
返回梳子;\r
}\r
\r
变种数组= [19,21,42,23,25,28];\r
\r
document.body.innerHTML + =< pre>中+ JSON.stringify(k_combinations(阵列,4),假的,\\ t的)+< / pre>中;
\r
I am trying to build a javascript function to get all combinations of size N from an array. lets say I got:
const Xarray = ["19", "21","42","23", "25", "28"];
const n = 4;
combinationsOfN(Xarray, n) =>
[ ["19", "21", "42", "23"],
["19", "21", "42", "25"],
["19", "21", "42", "28"],
["19", "21", "23", "25"],
["19", "21", "23", "28"],
["19", "21", "25", "28"],
…. ]
解决方案
Doing this by yourself might be rather tough, because I've tried that. There's already a js tool that does this for you, combinations.js
/**
* Copyright 2012 Akseli Palén.
* Created 2012-07-15.
* Licensed under the MIT license.
*/
function k_combinations(set, k) {
var i, j, combs, head, tailcombs;
if (k > set.length || k <= 0) {
return [];
}
if (k == set.length) {
return [set];
}
if (k == 1) {
combs = [];
for (i = 0; i < set.length; i++) {
combs.push([set[i]]);
}
return combs;
}
combs = [];
for (i = 0; i < set.length - k + 1; i++) {
head = set.slice(i, i+1);
tailcombs = k_combinations(set.slice(i + 1), k - 1);
for (j = 0; j < tailcombs.length; j++) {
combs.push(head.concat(tailcombs[j]));
}
}
return combs;
}
function combinations(set) {
var k, i, combs, k_combs;
combs = [];
for (k = 1; k <= set.length; k++) {
k_combs = k_combinations(set, k);
for (i = 0; i < k_combs.length; i++) {
combs.push(k_combs[i]);
}
}
return combs;
}
var array = ["19", "21","42","23", "25", "28"];
document.body.innerHTML += "<pre>" + JSON.stringify(k_combinations(array, 4), false, "\t") + "</pre>";
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