Java: Searches a value in an m x n matrix
Java Basic: Exercise-120 with Solution
Write a Java program that searches for a value in an m x n matrix.
Sample Solution:
Java Code:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
// Initialize the 'target' value for searching
int target = 0;
// Create a 3x3 matrix and populate it with values
int[][] matrix = new int[3][3];
for (int row = 0; row < 3; row++) {
for (int col = 0; col < 3; col++) {
matrix[row][col] = (1 + row * 3 + col);
}
}
// Display the contents of the matrix
for (int row = 0; row < 3; row++) {
for (int col = 0; col < 3; col++) {
System.out.print(matrix[row][col] + " ");
if (col == 2) {
System.out.println();
}
}
}
// Print the result of the 'searchMatrix' function
System.out.print(Boolean.toString(searchMatrix(matrix, target)));
}
public static boolean searchMatrix(int[][] matrix, int target) {
// Check if the matrix is empty or has no columns
if (matrix.length == 0 || matrix[0].length == 0) {
return false;
}
// Get the number of rows 'm' and columns 'n' in the matrix
int m = matrix.length;
int n = matrix[0].length;
// Initialize 'lower' and 'higher' for binary search
int lower = 0;
int higher = m * n - 1;
// Perform binary search to find 'target' in the matrix
while (lower <= higher) {
int mid = (lower + higher) >> 1;
int val = matrix[mid / n][mid % n];
if (val == target) {
return true;
}
if (val < target) {
lower = mid + 1;
} else {
higher = mid - 1;
}
}
// If 'target' is not found, return false
return false;
}
}
Sample Output:
1 2 3 4 5 6 7 8 9 false
Pictorial Presentation:
Flowchart:
Java Code Editor:
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