chore: add interpolation search

.github/workflows/testing.yml

@@ -22,5 +22,7 @@ jobs:
         run: zig build
 
       - name: Test project
-        run: zig build test --summary all
-
+        run: |
+          zig fmt --check .
+          zig build
+          zig build test --summary all

README.md

@@ -8,7 +8,7 @@ This repository contains implementations of various search and sort algorithms i
 
 - [x] Binary Search
 - [x] Jump Search
-- [ ] Interpolation Search
+- [x] Interpolation Search
 - [ ] Exponential Search
 - [ ] Fibonacci Search
 - [ ] Depth First Search (DFS)

src/root.zig

@@ -4,7 +4,9 @@ const testing = std.testing;
 test {
     _ = BinarySearch;
     _ = JumpSearch;
+    _ = InterpolationSearch;
 }
 
 pub const BinarySearch = @import("search/binary-search.zig");
 pub const JumpSearch = @import("search/jump-search.zig");
+pub const InterpolationSearch = @import("search/interpolation-search.zig");

src/search/interpolation-search.zig

@@ -0,0 +1,36 @@
+/// Interpolation search
+///
+/// time complexity:
+/// space complexity:
+const std = @import("std");
+const testing = std.testing;
+const utils = @import("search_utils.zig");
+const assertInteger = utils.assertInteger;
+
+pub fn search(array: anytype, target: @typeInfo(@TypeOf(array)).Array.child) ?@TypeOf(array[0]) {
+    assertInteger(@TypeOf(array));
+
+    var left: usize = 0;
+    var right: usize = array.len - 1;
+
+    while (left < right) {
+        const probe: usize = @intCast(@as(i64, @intCast(left)) + @divTrunc(@as(i64, @intCast(right - left)) * (target - array[left]), (array[right] - array[left])));
+
+        if (array[probe] == target) {
+            return target;
+        }
+        if (array[probe] < target) {
+            left = probe + 1;
+        }
+        if (array[probe] > target) {
+            right = probe;
+        }
+    }
+    return null;
+}
+
+test "test interpolation search" {
+    const array = [_]i64{ 1, 2, 4, 8, 16, 32, 64 };
+    try testing.expectEqual(null, search(array, 5));
+    try testing.expectEqual(4, search(array, 4));
+}

src/search/search_utils.zig

@@ -2,7 +2,7 @@ pub fn assertInteger(comptime T: type) void {
     switch (@typeInfo(T)) {
         .Array => |info| switch (@typeInfo(info.child)) {
             .ComptimeInt, .Int => return,
-            else => @compileError("not implemented for " ++ @typeName(T)),
+            else => @compileError("not implemented for " ++ @typeName(T) ++ ", expected integer"),
         },
         else => @compileError("expects an array instead of " ++ @typeName(T)),
     }