97 lines
1.6 KiB
JavaScript
97 lines
1.6 KiB
JavaScript
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/*
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Implement pow(x, n), which calculates x raised to the power n (xn).
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Example 1:
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Input: 2.00000, 10
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Output: 1024.00000
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Example 2:
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Input: 2.10000, 3
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Output: 9.26100
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Example 3:
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Input: 2.00000, -2
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Output: 0.25000
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Explanation: 2-2 = 1/22 = 1/4 = 0.25
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Note:
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-100.0 < x < 100.0
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n is a 32-bit signed integer, within the range [−231, 231 − 1]
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*/
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const { assert } = require('../../util/js');
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/**
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* @param {number} x
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* @param {number} n
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* @return {number}
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*/
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var myPow = function(x, n) {
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const isNeg = n < 0 ? true: false;
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if (n === 0) {
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return 1;
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}
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if (n === 1) {
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return x;
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}
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if (n === -1) {
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return 1/x;
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}
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const storedCalcs = {};
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const recursivePow = (x, n) => {
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if (n === 2) {
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return isNeg ? (1/x * 1/x) : x * x;
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}
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if (n === 1) {
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return isNeg ? 1/x : x;
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}
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if (n === 0) {
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return 1;
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}
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const firstHalf = Math.floor(parseInt(Math.abs(n) / 2));
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const secondHalf = Math.abs(n) - firstHalf;
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if(storedCalcs[n]) {
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return storedCalcs[n];
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}
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const result = recursivePow(x, firstHalf) * recursivePow(x, secondHalf);
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storedCalcs[n] = result;
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return result;
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};
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return recursivePow(x, n);
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}
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/* Test Case 1
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* Input: 2.00000, 10
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* Output: 1024.00000
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*/
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x = 2.00000;
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n = 10;
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sol = 1024.00000;
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assert(myPow(x, n) == sol, 'Output: 1024.00000');
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/* Test Case 2
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* Input: 2.10000, 3
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* Output: 9.261
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*/
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x = 2.10000;
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n = 3;
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sol = 9.261;
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assert(myPow(x, n).toFixed(3) == sol, 'Output: 9.261');
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/* Test Case 3
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* Input: 2.00000, -2
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* Output: 0.25
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*/
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x = 2.00000;
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n = -2;
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sol = 0.25;
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assert(myPow(x, n) == sol, 'Output: 0.25000');
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