Fix division by zero in interpolation search (#7484)

* Fix division by zero in interpolation search

* style: fix formatting in InterpolationSearchTest

Author: priyanshuvishwakarma273403

src/main/java/com/thealgorithms/searches/InterpolationSearch.java

@@ -36,9 +36,12 @@ public int find(int[] array, int key) {
         // Since array is sorted, an element present
         // in array must be in range defined by corner
         while (start <= end && key >= array[start] && key <= array[end]) {
+            if (array[start] == array[end]) {
+                return start;
+            }
             // Probing the position with keeping
             // uniform distribution in mind.
-            int pos = start + (((end - start) / (array[end] - array[start])) * (key - array[start]));
+            int pos = start + (int) (((long) (end - start) * (key - array[start])) / ((long) array[end] - array[start]));
 
             // Condition of target found
             if (array[pos] == key) {

src/test/java/com/thealgorithms/searches/InterpolationSearchTest.java

@@ -87,4 +87,15 @@ void testInterpolationSearchLargeNonUniformArray() {
         int key = 21; // Present in the array
         assertEquals(6, interpolationSearch.find(array, key), "The index of the found element should be 6.");
     }
+
+    /**
+     * Test for interpolation search with specific sorted arrays that previously caused division by zero.
+     */
+    @Test
+    void testInterpolationSearchDivisionByZeroEdgeCases() {
+        InterpolationSearch interpolationSearch = new InterpolationSearch();
+        assertEquals(3, interpolationSearch.find(new int[] {0, 0, 0, 2}, 2));
+        assertEquals(0, interpolationSearch.find(new int[] {2, 2, 2, 2}, 2));
+        assertEquals(3, interpolationSearch.find(new int[] {0, 1, 2, 4}, 4));
+    }
 }