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54 lines
1.8 KiB
Java
54 lines
1.8 KiB
Java
package com.thealgorithms.searches;
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/**
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* Program to perform Saddleback Search Given a sorted 2D array(elements are
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* sorted across every row and column, assuming ascending order) of size n*m we
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* can search a given element in O(n+m)
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*
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* <p>
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* we start from bottom left corner if the current element is greater than the
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* given element then we move up else we move right Sample Input: 5 5
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* ->Dimensions -10 -5 -3 4 9 -6 -2 0 5 10 -4 -1 1 6 12 2 3 7 8 13 100 120 130
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* 140 150 140 ->element to be searched output: 4 3 // first value is row,
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* second one is column
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*
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* @author Nishita Aggarwal
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*/
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public final class SaddlebackSearch {
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private SaddlebackSearch() {
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}
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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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* @throws IllegalArgumentException if the array is empty.
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* @return The index(row and column) of the element if found. Else returns
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* -1 -1.
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*/
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static int[] find(int[][] arr, int row, int col, int key) {
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if (arr.length == 0) {
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throw new IllegalArgumentException("Array is empty");
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}
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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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} // 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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