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SaddlebackSearch.java
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69 lines (64 loc) · 2.08 KB
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package Searches;
import java.util.Scanner;
/**
* Program to perform Saddleback Search Given a sorted 2D array(elements are sorted across every row
* and column, assuming ascending order) of size n*m we can search a given element in O(n+m)
*
* <p>we start from bottom left corner if the current element is greater than the given element then
* we move up else we move right Sample Input: 5 5 ->Dimensions -10 -5 -3 4 9 -6 -2 0 5 10 -4 -1 1 6
* 12 2 3 7 8 13 100 120 130 140 150 140 ->element to be searched output: 4 3 // first value is row,
* second one is column
*
* @author Nishita Aggarwal
*/
public class SaddlebackSearch {
/**
* This method performs Saddleback Search
*
* @param arr The **Sorted** array in which we will search the element.
* @param row the current row.
* @param col the current column.
* @param key the element that we want to search for.
* @return The index(row and column) of the element if found. Else returns -1 -1.
*/
private static int[] find(int arr[][], int row, int col, int key) {
// array to store the answer row and column
int ans[] = {-1, -1};
if (row < 0 || col >= arr[row].length) {
return ans;
}
if (arr[row][col] == key) {
ans[0] = row;
ans[1] = col;
return ans;
}
// if the current element is greater than the given element then we move up
else if (arr[row][col] > key) {
return find(arr, row - 1, col, key);
}
// else we move right
return find(arr, row, col + 1, key);
}
/**
* Main method
*
* @param args Command line arguments
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
int arr[][];
int i, j, rows = sc.nextInt(), col = sc.nextInt();
arr = new int[rows][col];
for (i = 0; i < rows; i++) {
for (j = 0; j < col; j++) {
arr[i][j] = sc.nextInt();
}
}
int ele = sc.nextInt();
// we start from bottom left corner
int ans[] = find(arr, rows - 1, 0, ele);
System.out.println(ans[0] + " " + ans[1]);
sc.close();
}
}