random array & shuffle
shuffle 洗牌算法 / 随机算法
https://en.wikipedia.org/wiki/Fisher–Yates_shuffle
ES6 version
"use strict";
/**
*
* @author xgqfrms
* @license MIT
* @copyright xgqfrms
* @created 2020-07-20
* @modified
*
* @description shuffle 洗牌算法
* @difficulty Easy
* @complexity O(n)
* @augments
* @example
* @link https://www.cnblogs.com/xgqfrms/p/11977189.html
* @solutions
*
*/
const log = console.log;
const shuffle = (arr = []) => {
let len = arr.length;
while (len > 1){
// Math.floor
const index = Math.floor(Math.random() * len--);
// ES6 swap
[
arr[len],
arr[index],
] = [
arr[index],
arr[len],
];
}
return arr;
}
const noForArrayAutoGenerator = (len = 100, type = `number`) => {
if (type === `number`) {
// number array
return [...``.padStart(len, ` `)].map((item, i) => i + 1);
} else if(`string`) {
// string array
return [...``.padStart(len, ` `)].map((item, i) => i + 1 + ``);
} else {
// mixed array
return [...``.padStart(len, ` `)].map((item, i) => i + 1).map((item, i) => i % 2 === 0 ? item : item + ``);
}
}
const arr = noForArrayAutoGenerator(10);
const test = shuffle(arr);
log(`test`, test);
ES5 version
function shuffle(arr) {
let m = arr.length;
while (m > 1){
let index = Math.floor(Math.random() * m--);
[arr[m] , arr[index]] = [arr[index] , arr[m]]
}
return arr;
}
// test
shuffle([1,2,3,4,5,6,7,8]);
prototype version
// Fisher–Yates shuffle
"use strict";
/**
*
* @author xgqfrms
* @license MIT
* @copyright xgqfrms
* @created 2020-07-20
* @modified
*
* @description shuffle 洗牌算法
* @difficulty Easy
* @complexity O(n)
* @augments
* @example
* @link https://www.cnblogs.com/xgqfrms/p/11977189.html
* @solutions
*
*/
const log = console.log;
// prototype
Array.prototype.shuffle = function() {
var arr = this;
log(`arr === this`, arr)
var len = arr.length;
for (let i = 0; i < len; i++) {
// randomIndex
var index = Math.floor(Math.random() * (i + 1));
// swap
var temp = arr[index];
arr[index] = arr[i];
arr[i] = temp;
}
return arr;
};
const noForArrayAutoGenerator = (len = 100, type = `number`) => {
if (type === `number`) {
// number array
return [...``.padStart(len, ` `)].map((item, i) => i + 1);
} else if(`string`) {
// string array
return [...``.padStart(len, ` `)].map((item, i) => i + 1 + ``);
} else {
// mixed array
return [...``.padStart(len, ` `)].map((item, i) => i + 1).map((item, i) => i % 2 === 0 ? item : item + ``);
}
}
const arr = noForArrayAutoGenerator(10);
// test
const test = arr.shuffle();
log(`test`, test);
demo
refs
https://codepen.io/xgqfrms/pen/Bayabba
https://gaohaoyang.github.io/2016/10/16/shuffle-algorithm/#top
https://juejin.im/post/5d004ad95188257c6b518056
©xgqfrms 2012-2020
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