search element in 2D matrix

Author: NirmalSilwal

CodingBlocks Training/Day14/searchMatrix2.java

@@ -0,0 +1,52 @@
+package Lecture14;
+
+public class searchMatrix2 {
+
+	public static void main(String[] args) {
+
+		int[][] arr = { { 10, 20, 30, 40 }, 
+						{ 11, 21, 31, 41 },
+						{ 12, 22, 32, 42 }, 
+						{ 13, 23, 33, 43 } };
+
+		System.out.println(searchKeyMatrix(arr, 22)); // true
+		System.out.println(searchKeyMatrix(arr, 10)); // true
+		System.out.println(searchKeyMatrix(arr, 42)); // true
+		System.out.println(searchKeyMatrix(arr, 23)); // true
+		System.out.println(searchKeyMatrix(arr, 13)); // true
+		System.out.println(searchKeyMatrix(arr, 2)); // false
+
+	}
+
+	public static boolean searchKeyMatrix(int[][] arr, int key) {
+		int start = 0, end = arr.length - 1;
+		int mid = (start + end) / 2;
+		if (arr[0][mid] == key || arr[mid][0] == key) {
+			return true;
+		}
+
+		int startcol = 0;
+		int endcol = arr.length - 1;
+		if (key < arr[0][mid]) {
+			endcol = mid;
+		} else {
+			startcol = mid;
+		}
+
+		int startrow = 0;
+		int endrow = arr.length - 1;
+		if (key < arr[mid][0]) {
+			endrow = mid;
+		} else {
+			startrow = mid;
+		}
+		for (int row = startrow; row <= endrow; row++) {
+			for (int col = startcol; col <= endcol; col++) {
+				if (arr[row][col] == key) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+}