85 lines
2.0 KiB
Java
85 lines
2.0 KiB
Java
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import java.util.*;
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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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*
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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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*/
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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 crow the current row.
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* @param ccol the current column.
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* @param ele the element that we want to search for.
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*
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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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static int[] search(int arr[][],int crow,int ccol,int ele){
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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(crow<0 || ccol>=arr[crow].length){
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return ans;
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}
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if(arr[crow][ccol]==ele)
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{
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ans[0]=crow;
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ans[1]=ccol;
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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[crow][ccol]>ele)
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{
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return search(arr,crow-1,ccol,ele);
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}
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//else we move right
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return search(arr,crow,ccol+1,ele);
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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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{
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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[]=search(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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