srchElementInSortedArrayBinarySrch.js

// Javascript program to find whether
// a given element is present
// in the given 2-D matrix

var M = 3;
var N = 4;

// Basic binary search to
// find an element in a 1-D array
function binarySearch1D(arr, K)
{
	var low = 0;
	var high = N - 1;
	while (low <= high) {
		var mid = low + parseInt((high - low) / 2);

		// if element found return true
		if (arr[mid] == K)
			return true;

		// if middle less than K then
		// skip the left part of the
		// array else skip the right part
		if (arr[mid] < K)
			low = mid + 1;
		else
			high = mid - 1;
	}

	// if not found return false
	return false;
}

// Function to search an element
// in a matrix based on
// Divide and conquer approach
function searchMatrix(matrix, K)
{
	var low = 0;
	var high = M - 1;
	while (low <= high) {
		var mid = low + parseInt((high - low) / 2);

		// if the element lies in the range
		// of this row then call
		// 1-D binary search on this row
		if (K >= matrix[mid][0]
			&& K <= matrix[mid][N - 1])
			return binarySearch1D(matrix[mid], K);

		// if the element is less than the
		// starting element of that row then
		// search in upper rows else search
		// in the lower rows
		if (K < matrix[mid][0])
			high = mid - 1;
		else
			low = mid + 1;
	}

	// if not found
	return false;
}

// Driver code
var matrix =      [ [ 1,  3,  5,  7  ],
					[ 10, 11, 16, 20 ],
					[ 23, 30, 34, 50 ] ];
var K = 3;
if (searchMatrix(matrix, K))
	console.log( "Found" );
else
console.log( "Not found" );