19JS输出杨辉三角

<!DOCTYPE html>

<head>

<title>Document</title>

</head>

<body>

function print(v) {

if (typeof v == "number") {

var w = 30;

if (n > 30) w = n - 30 + 40;

var s =

'<span style="padding:4px 2px;display:inline-block;text-align:center;width:' +

w +

'px;">' +

v +

"</span>";

document.write(s);

} else {

document.write(v);

}

var n = prompt("请输入幂数：", 9);

n = n - 0;

var t1 = new Date();

var a1 = [1, 1];

var a2 = [1, 1];

print('<div style=text-align:center;">');

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

for (var j = 1; j < i + 2; j++) {

print(c(i, j));

}

print("<br />");

}

print("</div>");

var t2 = new Date();

print(

"<p style='text-align:center;'>耗时为（毫秒）：" + (t2 - t1) + "</p>"

);

function c(x, y) {

if (y == 1 || y == x + 1) return 1;

return c(x - 1, y - 1) + c(x - 1, y);

}

</script>

</body>

</html>

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