Added Llinear Search, used Error-Set and 8 test cases. (#32)

* Added Selection Sort along with 9 test cases

* Added Linear Search

Author: Rexdy

CONTRIBUTING.md

@@ -39,6 +39,7 @@ Every project is managed by the `build.zig` file.
 ├── runall.sh
 ├── search
 │   ├── binarySearchTree.zig
+│   ├── linearSearch.zig
 │   └── redBlackTrees.zig
 ├── sort
 │   ├── bubbleSort.zig

build.zig

@@ -65,6 +65,13 @@ pub fn build(b: *std.Build) void {
             .name = "redBlackTrees.zig",
             .category = "search",
         });
+    if (std.mem.eql(u8, op, "search/linearSearch"))
+        buildAlgorithm(b, .{
+            .optimize = optimize,
+            .target = target,
+            .name = "linearSearch.zig",
+            .category = "search",
+        });
 
     // Data Structures algorithms
     if (std.mem.eql(u8, op, "ds/trie"))

runall.zig

@@ -38,6 +38,7 @@ pub fn main() !void {
     // Search
     try runTest(allocator, "search/bSearchTree");
     try runTest(allocator, "search/rb");
+    try runTest(allocator, "search/linearSearch");
 
     // Threads
     try runTest(allocator, "threads/threadpool");

search/linearSearch.zig

@@ -0,0 +1,56 @@
+const std = @import("std");
+const expect = std.testing.expect;
+const expectError = std.testing.expectError;
+
+const searchErrors = error{KeyNotFound};
+
+// returns the index of the first occurrence of key
+fn search(arr: []i32, key: i32) !usize {
+    for (arr, 0..) |v, i| {
+        if (v == key) {
+            return i;
+        }
+    }
+    return searchErrors.KeyNotFound;
+}
+
+test "empty array" {
+    var A = [_]i32{};
+    try expectError(searchErrors.KeyNotFound, search(A[0..], 5));
+}
+
+test "single element array, key not in array" {
+    var A = [_]i32{2};
+    try expectError(searchErrors.KeyNotFound, search(A[0..], 5));
+}
+
+// to test off-by-one errors
+test "2 element array" {
+    var A = [_]i32{ 2, 8 };
+    try expect(try search(A[0..], 8) == 1);
+}
+
+test "key at last" {
+    var A = [_]i32{ 2, 3, 6, 0, 1, 7, 8, 9 };
+    try expect(try search(A[0..], 9) == 7);
+}
+
+test "key not in array" {
+    var A = [_]i32{ 2, 3, 6, 0, 1, 7, 8, 9 };
+    try expectError(searchErrors.KeyNotFound, search(A[0..], 5));
+}
+
+test "duplicate elements in array" {
+    var A = [_]i32{ 2, 3, 6, 0, 1, 7, 8, 1, 9 };
+    try expect(try search(A[0..], 1) == 4);
+}
+
+test "negative numbers" {
+    var A = [_]i32{ 2, -3, 6, 0, 1, -7, 8, -1, 9 };
+    try expect(try search(A[0..], -1) == 7);
+}
+
+test "identical elements" {
+    var A = [_]i32{ 0, 0, 0, 0, 0, 0, 0, 0 };
+    try expect(try search(A[0..], 0) == 0);
+}