35 lines
825 B
JavaScript
35 lines
825 B
JavaScript
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const fibonacci = function(countArg) {
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// checks argument's type and makes sure we use
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// a number throughout rest of function.
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let count
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if (typeof countArg !== 'number') {
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count = parseInt(countArg)
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} else {
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count = countArg
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}
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if (count < 0) return "OOPS";
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if (count == 0) return 0;
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let firstPrev = 1;
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let secondPrev = 0;
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for (let i = 2; i <= count; i++) {
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let current = firstPrev + secondPrev;
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secondPrev = firstPrev;
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firstPrev = current;
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}
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return firstPrev;
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};
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// Another way to do it is by using an iterative approach with an array containing two values, 0 and 1.
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// const fib = [0, 1];
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// for (let i = 2; i <= count; i++) {
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// fib[i] = fib[i - 1] + fib[i - 2];
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// }
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// return fib[count];
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module.exports = fibonacci;
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