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27 lines
896 B
JavaScript
27 lines
896 B
JavaScript
/* Binary Search-Search a sorted array by repeatedly dividing the search interval
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* in half. Begin with an interval covering the whole array. If the value of the
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* search key is less than the item in the middle of the interval, narrow the interval
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* to the lower half. Otherwise narrow it to the upper half. Repeatedly check until the
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* value is found or the interval is empty.
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*/
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function binarySearch (arr, i) {
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var mid = Math.floor(arr.length / 2)
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if (arr[mid] === i) {
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console.log('match', arr[mid], i)
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return arr[mid]
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} else if (arr[mid] < i && arr.length > 1) {
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binarySearch(arr.splice(mid, Number.MAX_VALUE), i)
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} else if (arr[mid] > i && arr.length > 1) {
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binarySearch(arr.splice(0, mid), i)
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} else {
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console.log('not found', i)
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return -1
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}
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}
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var ar = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
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binarySearch(ar, 3)
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binarySearch(ar, 7)
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binarySearch(ar, 13)
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