Fix interpolationSearch looping forever when the seek element is above part of the range

src/algorithms/search/interpolation-search/__test__/interpolationSearch.test.js

@@ -21,4 +21,11 @@ describe('interpolationSearch', () => {
     expect(interpolationSearch([1, 2, 3, 700, 800, 1200, 1300, 1400, 19000], 800)).toBe(4);
     expect(interpolationSearch([0, 10, 11, 12, 13, 14, 15], 10)).toBe(1);
   });
+
+  it('should not loop forever when the seek element is missing and above part of the range', () => {
+    expect(interpolationSearch([2, 4, 8, 8, 10, 12, 18, 20, 20, 20, 22, 26, 26, 28], 24)).toBe(-1);
+    expect(interpolationSearch([1, 2, 3, 700, 800, 1200, 1300, 1400, 1900], 1500)).toBe(-1);
+    expect(interpolationSearch([1, 2, 3, 700, 800, 1200, 1300, 1400, 1900], 2000)).toBe(-1);
+    expect(interpolationSearch([1, 2, 3], 5)).toBe(-1);
+  });
 });

src/algorithms/search/interpolation-search/interpolationSearch.js

@@ -21,6 +21,14 @@ export default function interpolationSearch(sortedArray, seekElement) {
       return -1;
     }
 
+    // If the seek element is higher than the highest element of the range then
+    // there is nothing to find either. Without this check the interpolated
+    // middle index can land beyond rightIndex, "rightIndex = middleIndex - 1"
+    // then does not shrink the range and the loop never ends.
+    if (seekElement > sortedArray[rightIndex]) {
+      return -1;
+    }
+
     // If range delta is zero then subarray contains all the same numbers
     // and thus there is nothing to search for unless this range is all
     // consists of seek number.