diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/std/sort.zig | 116 |
1 files changed, 108 insertions, 8 deletions
diff --git a/lib/std/sort.zig b/lib/std/sort.zig index f8b8a39134..9fa7803cba 100644 --- a/lib/std/sort.zig +++ b/lib/std/sort.zig @@ -1189,24 +1189,124 @@ fn fuzzTest(rng: *std.rand.Random) void { } } -pub fn min(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool) T { - var i: usize = 0; +pub fn argMin(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) ?usize { + if (items.len == 0) { + return null; + } + var smallest = items[0]; - for (items[1..]) |item| { + var smallest_index: usize = 0; + for (items[1..]) |item, i| { if (lessThan(item, smallest)) { smallest = item; + smallest_index = i + 1; } } - return smallest; + + return smallest_index; } -pub fn max(comptime T: type, items: []T, lessThan: fn (lhs: T, rhs: T) bool) T { - var i: usize = 0; +test "std.sort.argMin" { + testing.expectEqual(@as(?usize, null), argMin(i32, &[_]i32{}, asc(i32))); + testing.expectEqual(@as(?usize, 0), argMin(i32, &[_]i32{1}, asc(i32))); + testing.expectEqual(@as(?usize, 0), argMin(i32, &[_]i32{ 1, 2, 3, 4, 5 }, asc(i32))); + testing.expectEqual(@as(?usize, 3), argMin(i32, &[_]i32{ 9, 3, 8, 2, 5 }, asc(i32))); + testing.expectEqual(@as(?usize, 0), argMin(i32, &[_]i32{ 1, 1, 1, 1, 1 }, asc(i32))); + testing.expectEqual(@as(?usize, 0), argMin(i32, &[_]i32{ -10, 1, 10 }, asc(i32))); + testing.expectEqual(@as(?usize, 3), argMin(i32, &[_]i32{ 6, 3, 5, 7, 6 }, desc(i32))); +} + +pub fn min(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) ?T { + const i = argMin(T, items, lessThan) orelse return null; + return items[i]; +} + +test "std.sort.min" { + testing.expectEqual(@as(?i32, null), min(i32, &[_]i32{}, asc(i32))); + testing.expectEqual(@as(?i32, 1), min(i32, &[_]i32{1}, asc(i32))); + testing.expectEqual(@as(?i32, 1), min(i32, &[_]i32{ 1, 2, 3, 4, 5 }, asc(i32))); + testing.expectEqual(@as(?i32, 2), min(i32, &[_]i32{ 9, 3, 8, 2, 5 }, asc(i32))); + testing.expectEqual(@as(?i32, 1), min(i32, &[_]i32{ 1, 1, 1, 1, 1 }, asc(i32))); + testing.expectEqual(@as(?i32, -10), min(i32, &[_]i32{ -10, 1, 10 }, asc(i32))); + testing.expectEqual(@as(?i32, 7), min(i32, &[_]i32{ 6, 3, 5, 7, 6 }, desc(i32))); +} + +pub fn argMax(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) ?usize { + if (items.len == 0) { + return null; + } + var biggest = items[0]; - for (items[1..]) |item| { + var biggest_index: usize = 0; + for (items[1..]) |item, i| { if (lessThan(biggest, item)) { biggest = item; + biggest_index = i + 1; } } - return biggest; + + return biggest_index; +} + +test "std.sort.argMax" { + testing.expectEqual(@as(?usize, null), argMax(i32, &[_]i32{}, asc(i32))); + testing.expectEqual(@as(?usize, 0), argMax(i32, &[_]i32{1}, asc(i32))); + testing.expectEqual(@as(?usize, 4), argMax(i32, &[_]i32{ 1, 2, 3, 4, 5 }, asc(i32))); + testing.expectEqual(@as(?usize, 0), argMax(i32, &[_]i32{ 9, 3, 8, 2, 5 }, asc(i32))); + testing.expectEqual(@as(?usize, 0), argMax(i32, &[_]i32{ 1, 1, 1, 1, 1 }, asc(i32))); + testing.expectEqual(@as(?usize, 2), argMax(i32, &[_]i32{ -10, 1, 10 }, asc(i32))); + testing.expectEqual(@as(?usize, 1), argMax(i32, &[_]i32{ 6, 3, 5, 7, 6 }, desc(i32))); +} + +pub fn max(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) ?T { + const i = argMax(T, items, lessThan) orelse return null; + return items[i]; +} + +test "std.sort.max" { + testing.expectEqual(@as(?i32, null), max(i32, &[_]i32{}, asc(i32))); + testing.expectEqual(@as(?i32, 1), max(i32, &[_]i32{1}, asc(i32))); + testing.expectEqual(@as(?i32, 5), max(i32, &[_]i32{ 1, 2, 3, 4, 5 }, asc(i32))); + testing.expectEqual(@as(?i32, 9), max(i32, &[_]i32{ 9, 3, 8, 2, 5 }, asc(i32))); + testing.expectEqual(@as(?i32, 1), max(i32, &[_]i32{ 1, 1, 1, 1, 1 }, asc(i32))); + testing.expectEqual(@as(?i32, 10), max(i32, &[_]i32{ -10, 1, 10 }, asc(i32))); + testing.expectEqual(@as(?i32, 3), max(i32, &[_]i32{ 6, 3, 5, 7, 6 }, desc(i32))); +} + +pub fn isSorted(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) bool { + var i: usize = 1; + while (i < items.len) : (i += 1) { + if (lessThan(items[i], items[i - 1])) { + return false; + } + } + + return true; +} + +test "std.sort.isSorted" { + testing.expect(isSorted(i32, &[_]i32{}, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{10}, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 1, 2, 3, 4, 5 }, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{ -10, 1, 1, 1, 10 }, asc(i32))); + + testing.expect(isSorted(i32, &[_]i32{}, desc(i32))); + testing.expect(isSorted(i32, &[_]i32{-20}, desc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 3, 2, 1, 0, -1 }, desc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 10, -10 }, desc(i32))); + + testing.expect(isSorted(i32, &[_]i32{ 1, 1, 1, 1, 1 }, asc(i32))); + testing.expect(isSorted(i32, &[_]i32{ 1, 1, 1, 1, 1 }, desc(i32))); + + testing.expectEqual(false, isSorted(i32, &[_]i32{ 5, 4, 3, 2, 1 }, asc(i32))); + testing.expectEqual(false, isSorted(i32, &[_]i32{ 1, 2, 3, 4, 5 }, desc(i32))); + + testing.expect(isSorted(u8, "abcd", asc(u8))); + testing.expect(isSorted(u8, "zyxw", desc(u8))); + + testing.expectEqual(false, isSorted(u8, "abcd", desc(u8))); + testing.expectEqual(false, isSorted(u8, "zyxw", asc(u8))); + + testing.expect(isSorted(u8, "ffff", asc(u8))); + testing.expect(isSorted(u8, "ffff", desc(u8))); } |