How Interpolation Search Works
index 016 of 16 still possible15
- Ruled out
- Still possible
- Checked now
- Found
1/3
Looking for 158 in 16 sorted values, from 4 to 196.
Settings
More options
Is it in the array?
Gaps between values
Two to 64 numbers. Sorted ascending before the search runs.
Interpolation Search
- 1
while a[lo] <= target <= a[hi]: - 2
// guess where the value should sit - 3
pos = lo + (target - a[lo]) - 4
* (hi - lo) / (a[hi] - a[lo]) - 5
if a[pos] == target: return pos - 6
if a[pos] < target: lo = pos + 1 - 7
else: hi = pos - 1 - 8
return NOT_FOUND
How the Six Compare
| Algorithm | Best | Average | Worst | Needs a sorted array |
|---|---|---|---|---|
| Linear | O(1) | O(n) | O(n) | No |
| Binary | O(1) | O(log n) | O(log n) | Yes |
| Ternary | O(1) | O(log n) | O(log n) | Yes |
| Jump | O(1) | O(√n) | O(√n) | Yes |
| Exponential | O(1) | O(log n) | O(log n) | Yes |
| Interpolation | O(1) | O(log log n)* | O(n) | Yes |
Scroll the table sideways for the rest of the columns.
Interpolation search only reaches that average when the gaps between the values are even.