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turtle-noturtle.html
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turtle-noturtle.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Turtle First</title>
<style>
html {
font-family: 'Courier New', Courier, monospace;
}
table.gridtable {
font-family: verdana, arial, sans-serif;
font-size: 11px;
color: #333333;
border-width: 1px;
border-color: #666666;
border-collapse: collapse;
}
table.gridtable td {
text-align: left;
width: 10px;
border-width: 1px;
padding: 2px;
border-style: solid;
border-color: #666666;
background-color: #ffffff;
}
</style>
</head>
<body>
<script type="text/javascript">
// 累加累乘斐波那契九九表n皇后
function sum() {
let n = 0
for (let i = 1; i <= 50000; i++) {
n += i
}
document.write(`累加到50000: ${n}<br>`)
}
function mul() {
let n = 1n
for (let i = 2n; i <= 50n; i++) {
n *= i
}
document.write(`累乘到50: ${n}<br>`)
}
function fibonacci(n) {
if (n === 0) {
return 0
} else if (n === 1) {
return 1
} else {
return fibonacci(n - 1) + fibonacci(n - 2)
}
}
function fibNoCache() {
let d = +new Date()
document.write(
'硬算Fib(40): ' + fibonacci(40) + ',' + (+new Date() - d) + '<br>'
)
}
function fibonacciMemoized(n, memo = {}) {
if (n in memo) {
return memo[n]
}
if (n === 0n) {
return 0n
} else if (n === 1n) {
return 1n
}
memo[n] =
fibonacciMemoized(n - 1n, memo) + fibonacciMemoized(n - 2n, memo)
return memo[n]
}
function fibMemo() {
let d = +new Date()
document.write(
'缓存算Fib(50n): ' +
fibonacciMemoized(50n) +
',' +
(+new Date() - d) +
'<br>'
)
}
function nineTable() {
document.write('<br>')
document.write('九九表<br>')
for (let i = 1; i <= 9; i++) {
for (let k = i; k <= 9; k++) {
let val = k * i
document.write(
`${i}x${k} = ${val < 10 ? ' ' + val : val} `
)
}
document.write('<br>')
}
}
function solveNQueens(size = 8) {
const solutions = []
function backtrack(row, cols = 0, d1 = 0, d2 = 0, board = []) {
// 如果已经处理完最后一行，即找到了一种解决方案，将其加入 solutions 数组
if (row === size) {
solutions.push(board.map(cols => cols.join('</td><td>')))
return
}
for (let col = 0, mask; col < size; col++) {
mask = 1 << col // 创建当前列的位掩码
if (
!(cols & mask) &&
!(d1 & (1 << (row + col))) &&
!(d2 & (1 << (row - col + size - 1)))
) {
board.push(
Array(size)
.fill('.')
.fill('Q', col, col + 1)
) // 将皇后放置在棋盘上
backtrack(
row + 1,
cols | mask,
d1 | (1 << (row + col)),
d2 | (1 << (row - col + size - 1)),
board
)
board.pop()
}
}
}
backtrack(0)
return solutions
}
function printNqueens() {
const size = 6
document.write(`${size}皇后问题<br>`)
solveNQueens(size).map((x, idx) => {
document.write(`第${idx + 1}种解法<br>`)
document.write(
`<table id=t${idx} class="gridtable"><tr><td>${x.join(
'</td></tr><tr><td>'
)}</td></tr></table>`
)
document.querySelector(`#t${idx}`).style.width = size * 18 + 'px'
document.write('<br>')
})
}
sum()
mul()
fibNoCache()
fibMemo()
nineTable()
printNqueens()
</script>
</body>
</html>