35 lines
1.0 KiB
JavaScript
35 lines
1.0 KiB
JavaScript
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/* In this We will learn how to search for an item in Sorted array using Binary Search .*/
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function binarySearch( item , arr ) {
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let first = 0; //left endpoint or index of first array element
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let last = arr.length - 1; //right endpoint or index of lat array element .
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while (first <= last) {
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let middle = Math.floor((first + last)/2);
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if ( arr[middle] == item ) {
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// If the element is present at the middle itself
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return middle ;
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}
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else if ( arr[middle] > item ) {
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// Ignore Right Half i.e. items after middle element .
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last = middle - 1;
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}
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else {
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// Ignore Right Half i.e. items after middle element .
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first = middle + 1;
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}
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}
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return -1; //Item is not present in Array .
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}
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console.log(binarySearch(6,[2, 6, 8])); //expected output = 1
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console.log(binarySearch(10,[2, 3, 10, 14])); //expected output = 2
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console.log(binarySearch(1,[2, 6, 8])); //expected output = -1
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