前端js 算法收集

by 前端开发者 · Published 2018年9月11日20:35:04 · Updated 2018年9月11日21:07:02

摘要：js模拟螺旋矩形算法代码片段 1 <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”> <html xmlns=……

js模拟螺旋矩形算法
代码片段 1

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>

<head>

<title> new document </title>

</head>

<body>

var cal = function (len) {

var helix = [[], [], [], [], [], []];

var min = 0;

var max = len – 1;

var row = 0;

var col = 0;

for (var i = 0; i < len * len; i++) {

helix[row][col] = i + 1;

if (row == min && col < max) {

col = col + 1;

}

else if (row < max && col == max) {

row = row + 1;

}

else if (row == max && col > min) {

col = col – 1;

}

else if (row > min && col == min) {

row = row – 1;

}

if (row – 1 == min && col == min) {

min = min + 1;

max = max – 1;

}

return helix;

};

var helix = cal(6);

var html = ”;

for (var i = 0; i < helix.length; i++) {

for (var j = 0; j < helix[i].length; j++) {

if (helix[i][j] < 10) {

helix[i][j] = “0” + helix[i][j];

}

html += helix[i][j] + ‘ ‘;

}

html += ”;

}

var container = document.getElementById(“container”);

container.innerHTML = html;

</script>

</body>

</html>

    js最短路径

代码片段 2

<html>

<head>

</head>

written by hjjboy

email:tianmashuangyi@163.com

qq:156809986

var closelist = new Array(), openlist = new Array();

var gw = 10, gh = 10, gwh = 14;

var p_start = new Array(2), p_end = new Array(2);

var s_path, n_path = “”;

var num, bg, flag = 0;

var w = 30, h = 20;

function GetRound(pos) {

var a = new Array();

a[0] = (pos[0] + 1) + “,” + (pos[1] – 1);

a[1] = (pos[0] + 1) + “,” + pos[1];

a[2] = (pos[0] + 1) + “,” + (pos[1] + 1);

a[3] = pos[0] + “,” + (pos[1] + 1);

a[4] = (pos[0] – 1) + “,” + (pos[1] + 1);

a[5] = (pos[0] – 1) + “,” + pos[1];

a[6] = (pos[0] – 1) + “,” + (pos[1] – 1);

a[7] = pos[0] + “,” + (pos[1] – 1);

return a;

}

function GetF(arr) {

var t, G, H, F;

for (var i = 0; i < arr.length; i++) {

t = arr[i].split(“,”);

t[0] = parseInt(t[0]); t[1] = parseInt(t[1]);

if (IsOutScreen([t[0], t[1]]) || IsPass(arr[i]) || InClose([t[0], t[1]]) || IsStart([t[0], t[1]]) || !IsInTurn([t[0], t[1]]))

continue;

if ((t[0] – s_path[3][0]) * (t[1] – s_path[3][1]) != 0)

G = s_path[1] + gwh;

else

G = s_path[1] + gw;

if (InOpen([t[0], t[1]])) {

if (G < openlist[num][1]) {

openlist[num][0] = (G + openlist[num][2]);

openlist[num][1] = G;

openlist[num][4] = s_path[3];

}

else { G = openlist[num][1]; }

}

else {

H = (Math.abs(p_end[0] – t[0]) + Math.abs(p_end[1] – t[1])) * gw;

F = G + H;

arr[i] = new Array();

arr[i][0] = F; arr[i][1] = G; arr[i][2] = H; arr[i][3] = [t[0], t[1]]; arr[i][4] = s_path[3];

openlist[openlist.length] = arr[i];

}

if (maptt.rows[t[1]].cells[t[0]].style.backgroundColor != “#cccccc” && maptt.rows[t[1]].cells[t[0]].style.backgroundColor != “#0000ff” && maptt.rows[t[1]].cells[t[0]].style.backgroundColor != “#ff0000” && maptt.rows[t[1]].cells[t[0]].style.backgroundColor != “#00ff00”) {

maptt.rows[t[1]].cells[t[0]].style.backgroundColor = “#FF00FF”;

//maptt.rows[t[1]].cells[t[0]].innerHTML=”<font color=white>”+G+”</font>”;

}

function IsStart(arr) {

if (arr[0] == p_start[0] && arr[1] == p_start[1])

return true;

return false;

}

function IsInTurn(arr) {

if (arr[0] > s_path[3][0]) {

if (arr[1] > s_path[3][1]) {

if (IsPass((arr[0] – 1) + “,” + arr[1]) || IsPass(arr[0] + “,” + (arr[1] – 1)))

return false;

}

else if (arr[1] < s_path[3][1]) {

if (IsPass((arr[0] – 1) + “,” + arr[1]) || IsPass(arr[0] + “,” + (arr[1] + 1)))

return false;

}

else if (arr[0] < s_path[3][0]) {

if (arr[1] > s_path[3][1]) {

if (IsPass((arr[0] + 1) + “,” + arr[1]) || IsPass(arr[0] + “,” + (arr[1] – 1)))

return false;

}

else if (arr[1] < s_path[3][1]) {

if (IsPass((arr[0] + 1) + “,” + arr[1]) || IsPass(arr[0] + “,” + (arr[1] + 1)))

return false;

}

return true;

}

function IsOutScreen(arr) {

if (arr[0] < 0 || arr[1] < 0 || arr[0] > (w – 1) || arr[1] > (h – 1))

return true;

return false;

}

function InOpen(arr) {

var bool = false;

for (var i = 0; i < openlist.length; i++) {

if (arr[0] == openlist[i][3][0] && arr[1] == openlist[i][3][1]) {

bool = true; num = i; break;

}

return bool;

}

function InClose(arr) {

var bool = false;

for (var i = 0; i < closelist.length; i++) {

if ((arr[0] == closelist[i][3][0]) && (arr[1] == closelist[i][3][1])) {

bool = true; break;

}

return bool;

}

function IsPass(pos) {

if ((“;” + n_path + “;”).indexOf(“;” + pos + “;”) != -1)

return true;

return false;

}

function Sort(arr) {

var temp;

for (var i = 0; i < arr.length; i++) {

if (arr.length == 1) break;

if (arr[i][0] <= arr[i + 1][0]) {

temp = arr[i];

arr[i] = arr[i + 1];

arr[i + 1] = temp;

}

if ((i + 1) == (arr.length – 1))

break;

}

function main() {

GetF(GetRound(s_path[3]));

Sort(openlist);

s_path = openlist[openlist.length – 1];

closelist[closelist.length] = s_path;

openlist[openlist.length – 1] = null;

if (openlist.length == 0) { alert(“找不到路径”); return; }

openlist.length = openlist.length – 1;

if ((s_path[3][0] == p_end[0]) && (s_path[3][1] == p_end[1])) {

getPath();

}

else { maptt.rows[s_path[3][1]].cells[s_path[3][0]].style.backgroundColor = “#00ff00”; setTimeout(“main()”, 100); }

}

function getPath() {

var str = “”;

var t = closelist[closelist.length – 1][4];

while (1) {

str += t.join(“,”) + “;”;

maptt.rows[t[1]].cells[t[0]].style.backgroundColor = “#ffff00”;

for (var i = 0; i < closelist.length; i++) {

if (closelist[i][3][0] == t[0] && closelist[i][3][1] == t[1])

t = closelist[i][4];

}

if (t[0] == p_start[0] && t[1] == p_start[1])

break;

}

alert(str);

}

function setPos() {

var h = (Math.abs(p_end[0] – p_start[0]) + Math.abs(p_end[1] – p_start[1])) * gw;

s_path = [h, 0, h, p_start, p_start];

}

function set(id, arr) {

switch (id) {

case 1:

p_start = arr;

maptt.rows[arr[1]].cells[arr[0]].style.backgroundColor = “#ff0000”; break;

case 2:

p_end = arr; maptt.rows[arr[1]].cells[arr[0]].style.backgroundColor = “#0000ff”; break;

case 3:

n_path += arr.join(“,”) + “;”; maptt.rows[arr[1]].cells[arr[0]].style.backgroundColor = “#cccccc”; break;

default:

break;

}

function setflag(id) { flag = id; }

</script>

for (var i = 0; i < h; i++) {

document.write(“<tr>”);

for (var j = 0; j < w; j++) {

document.write(‘<td onclick=”set(flag,[‘ + j + ‘,’ + i + ‘]);” bgcolor=”#ffffff” width=”20″ height=”20″></td>’);

}

document.write(“</tr>”);

}

</script>

</table>

<a href=’javascript:setflag(3);’>设置障碍点</a><br>

</body>

</html>

   js_常见排序算法

代码片段 3

<html>

<head>

Array.prototype.swap = function (i, j) {

var temp = this[i];

this[i] = this[j];

this[j] = temp;

}

Array.prototype.bubbleSort = function () {

for (var i = this.length – 1; i > 0; –i) {

for (var j = 0; j < i; ++j) {

if (this[j] > this[j + 1]) this.swap(j, j + 1);

}

Array.prototype.selectionSort = function () {

for (var i = 0; i < this.length; ++i) {

var index = i;

for (var j = i + 1; j < this.length; ++j) {

if (this[j] < this[index]) index = j;

}

this.swap(i, index);

}

Array.prototype.insertionSort = function () {

for (var i = 1; i < this.length; ++i) {

var j = i, value = this[i];

while (j > 0 && this[j – 1] > value) {

this[j] = this[j – 1];

–j;

}

this[j] = value;

}

Array.prototype.shellSort = function () {

for (var step = this.length >> 1; step > 0; step >>= 1) {

for (var i = 0; i < step; ++i) {

for (var j = i + step; j < this.length; j += step) {

var k = j, value = this[j];

while (k >= step && this[k – step] > value) {

this[k] = this[k – step];

k -= step;

}

this[k] = value;

}

Array.prototype.quickSort = function (s, e) {

if (s == null) s = 0;

if (e == null) e = this.length – 1;

if (s >= e) return;

this.swap((s + e) >> 1, e);

var index = s – 1;

for (var i = s; i <= e; ++i) {

if (this[i] <= this[e]) this.swap(i, ++index);

}

this.quickSort(s, index – 1);

this.quickSort(index + 1, e);

}

Array.prototype.stackQuickSort = function () {

var stack = [0, this.length – 1];

while (stack.length > 0) {

var e = stack.pop(), s = stack.pop();

if (s >= e) continue;

this.swap((s + e) >> 1, e);

var index = s – 1;

for (var i = s; i <= e; ++i) {

if (this[i] <= this[e]) this.swap(i, ++index);

}

stack.push(s, index – 1, index + 1, e);

}

Array.prototype.mergeSort = function (s, e, b) {

if (s == null) s = 0;

if (e == null) e = this.length – 1;

if (b == null) b = new Array(this.length);

if (s >= e) return;

var m = (s + e) >> 1;

this.mergeSort(s, m, b);

this.mergeSort(m + 1, e, b);

for (var i = s, j = s, k = m + 1; i <= e; ++i) {

b[i] = this[(k > e || j <= m && this[j] < this[k]) ? j++ : k++];

}

for (var i = s; i <= e; ++i) this[i] = b[i];

}

Array.prototype.heapSort = function () {

for (var i = 1; i < this.length; ++i) {

for (var j = i, k = (j – 1) >> 1; k >= 0; j = k, k = (k – 1) >> 1) {

if (this[k] >= this[j]) break;

this.swap(j, k);

}

for (var i = this.length – 1; i > 0; –i) {

this.swap(0, i);

for (var j = 0, k = (j + 1) << 1; k <= i; j = k, k = (k + 1) << 1) {

if (k == i || this[k] < this[k – 1])–k;

if (this[k] <= this[j]) break;

this.swap(j, k);

}

function generate() {

var max = parseInt(txtMax.value), count = parseInt(txtCount.value);

if (isNaN(max) || isNaN(count)) {

alert(“个数和最大值必须是一个整数”);

return;

}

var array = [];

for (var i = 0; i < count; ++i) array.push(Math.round(Math.random() * max));

array.push(“９９”);

txtInput.value = array.join(” “);

txtOutput.value = “”;

}

function demo(type) {

var array = txtInput.value == “” ? [] : txtInput.value.replace().split(” “);

for (var i = 0; i < array.length; ++i) array[i] = parseInt(array[i]);

var t1 = new Date();

eval(“array.” + type + “Sort()”);

var t2 = new Date();

lblTime.innerText = t2.valueOf() – t1.valueOf();

txtOutput.value = array.join(” “);

}

function search() {

var txtSearch = document.getElementById(“txtSearch”);

var array = txtInput.value == “” ? [] : txtInput.value.replace().split(” “);

var arrayResult = new Array();

var t1 = new Date();

alert(array.length);

for (var i = 0; i < array.length; ++i) {

if (array[i].indexOf(txtSearch.value) >= 0) {

arrayResult.push(array[i]);

}

//eval(“array.” + type + “Sort()”);

var t2 = new Date();

lblTime.innerText = t2.valueOf() – t1.valueOf();

txtOutput.value = arrayResult.join(” “);

}

</script>

</head>

<tr>

</td>

检索 <input id=”txtSearch” value=”” style=”width:50px”><br><br>

随机数个数<input id=txtCount value=500 style=”width:50px”><br><br>

最大随机数<input id=txtMax value=1000 style=”width:50px”><br><br>

耗时(毫秒)：<label id=lblTime></label><br><br><br><br>

</td>

</td>

</tr>

</table>

</body>

</html>

    这是网上的例子，感觉好头疼啊，有没有算法教程，我看那书里面都没有讲解的啊！
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