Merge pull request deutranium#224 from Abhishek-Greninja17/patch-1

Create  InterpolationSearch.java

Author: codelixir

searchingAlgo/interpolationSearch/InterpolationSearch.java

@@ -0,0 +1,101 @@
+import java.util.*;
+/* Interpolation Search: 
+    Condition: 
+    array or vector should be sorted of n uniformly distributed value
+    * sorted : in a sequence of either increasing or decreasing
+    * uniformly distributed : difference between every consecutive element must be same
+    * consecutive element difference : arr[8]-arr[7] = arr[2]-arr[1] = .. so on
+    
+    terminolgy used: 
+    arr : int arr 
+    n : given element to be searched
+    lo : starting index
+    hi : ending index
+    
+    Logic used: 
+    * recursion
+*/
+class InterpolationSearch {
+	public static int interpolationSearch(int arr[], int lo,int hi, int x)
+	{
+		int pos;
+		if (lo <= hi && x >= arr[lo] && x <= arr[hi]) 
+		{
+			pos = lo + (((hi - lo) / (arr[hi] - arr[lo])) * (x - arr[lo]));
+
+			if (arr[pos] == x)
+				return pos;
+			if (arr[pos] < x) //x is in right sub array as is closer to hi
+				return interpolationSearch(arr, pos + 1, hi, x); //dividing in right half
+			if (arr[pos] > x) //x is in left sub array as is closer to lo
+				return interpolationSearch(arr, lo, pos - 1, x); //dividing in left half
+		}
+		return -1;
+	}
+
+	// Driver Code
+	public static void main(String[] args)
+	{
+	    //test cases:
+    	/*  to print the index of the Element searched in the array 
+    	    starting from 0 and to print -1 if the element is not 
+    	    found.
+    	    
+    	    ** diff : |arr[n]-arr[n-1]|
+    	*/
+    	
+    	//test case 1 : all pos int with diff=1
+	    int arr1[] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19};
+		int n = arr1.length;
+		int x = 17;	// Element to be searched
+		int res = interpolationSearch(arr1, 0, n - 1, x);
+		System.out.println(res);
+
+		//test case 2 : with negative numbers with diff=1
+	    int arr2[] = { -5,-4,-3,-2,-1,0,1,2,3,4,5,6,7};
+		n = arr2.length;
+		x = -2;	// Element to be searched
+		res = interpolationSearch(arr2, 0, n - 1, x);
+		System.out.println(res);
+
+		//test case 3 : diff=5
+	    int arr3[] = { -15,-10,-5,0,5,10};
+		n = arr3.length;
+		x = 5;	// Element to be searched
+		res = interpolationSearch(arr3, 0, n - 1, x);
+		System.out.println(res);
+
+		//test case 4 : element not found
+	    int arr4[] = { -15,-10,-5,0,5,10,15,20};
+		n = arr4.length;
+		x = -2;	// Element to be searched
+		res = interpolationSearch(arr4, 0, n - 1, x);
+		System.out.println(res);
+
+        //conditions check: 
+        
+		//test case 5 : unsorted
+    	// unsorted thus will provide inconsistent solution (may give correct or may not)
+    	int arr5[] = {1,7,-8, 23, 6};
+		n = arr5.length;
+		x = 6;	// Element to be searched
+		res = interpolationSearch(arr5, 0, n - 1, x);
+		System.out.println(res);
+
+		//test case 6 : variable difference
+	    // sorted not uniformly increasing or decreasing thus won't be able to find
+	    int arr6[] = {1,2,4,7,9,2};
+		n = arr6.length;
+		x = 7;	// Element to be searched
+		res = interpolationSearch(arr6, 0, n - 1, x);
+		System.out.println(res);
+
+		//test case 7 : diff=0 (same elements) 
+	    // sorted not uniformly increasing or decreasing thus will provide garbage or null value
+		int arr7[] = {0,0,0,0,0,0,0,0,0,0,0};
+		n = arr7.length;
+		x = 17;	// Element to be searched
+		res = interpolationSearch(arr7, 0, n - 1, x);
+		System.out.println(res);
+	}
+}