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