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剑指Offer16.数值的整数次方.html
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剑指Offer16.数值的整数次方.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>剑指 Offer 16. 数值的整数次方</title>
</head>
<body>
<script>
// https://leetcode-cn.com/problems/shu-zhi-de-zheng-shu-ci-fang-lcof/
// 实现 pow(x, n) ,即计算 x 的 n 次幂函数(即,xn)。不得使用库函数,同时不需要考虑大数问题。
// 提示:
// -100.0 < x < 100.0
// -231 <= n <= 231-1
// -104 <= xn <= 104
/**
* @param {number} x
* @param {number} n
* @return {number}
*/
var myPow = function (x, n) {};
// --- answer-1 ---
// 快速幂
var myPow = function (x, n) {
if (n === 0) return 1;
if (n < 0) {
x = 1 / x;
n = -n;
}
let res = 1;
while (n > 0) {
if (n & 1) {
res *= x;
}
// 这里使用>>越界了 2147483648 >> 1 === -1073741824
n = Math.floor(n / 2) ;
x = x * x;
}
return res;
};
// --- answer-1 ---
// --- answer-2 ---
// --- answer-2 ---
var x = 2.0,
n = 10;
var result = 1024.0;
var x = 2.1,
n = 3;
var result = 9.261;
var x = 2.0,
n = -2;
var result = 0.25;
// 解释:2-2 = 1/22 = 1/4 = 0.25
var x = 2.0,
n = -2147483648;
var result = 0;
console.log("x = ", x);
console.log("n = ", n);
console.log("result = ", result);
console.log("myPow = ", myPow(x, n));
</script>
</body>
</html>