Commit 100b8a244cdbcd16669e6b81ab82d6a628559e22 | zig

author	Mikhail Popov <mpopov@fastmail.fm> 2021-10-22 14:38:08+02:00
committer	Veikka Tuominen <git@vexu.eu> 2022-01-27 21:22:00+02:00
log	100b8a244cdbcd16669e6b81ab82d6a628559e22
tree	9ceea7c580e5457487e129c237ef472db65f33ab
parent	dddbd2f511f505ad4018ba007f065ea2b4ec8f79

Add std.mem.minMax() and std.mem.IndexOfMinMax()

For finding the minimum and maximum values (and indices)
in a slice in a single pass.

1 files changed, 48 insertions(+), 0 deletions(-)

lib
- std
  - mem.zig

lib/std/mem.zig+48

...	...	@@ -2174,6 +2174,26 @@ test "mem.max" {
2174	2174	try testing.expectEqual(max(u8, "g"), 'g');
2175	2175	}
2176	2176
	2177	/// Finds the smallest and largest number in a slice. O(n).
	2178	/// Returns an anonymous struct with the fields `min` and `max`.
	2179	/// `slice` must not be empty.
	2180	pub fn minMax(comptime T: type, slice: []const T) struct { min: T, max: T } {
	2181	assert(slice.len > 0);
	2182	var minVal = slice[0];
	2183	var maxVal = slice[0];
	2184	for (slice[1..]) \|item\| {
	2185	minVal = math.min(minVal, item);
	2186	maxVal = math.max(maxVal, item);
	2187	}
	2188	return .{ .min = minVal, .max = maxVal };
	2189	}
	2190
	2191	test "mem.minMax" {
	2192	try testing.expectEqual(minMax(u8, "abcdefg"), .{ .min = 'a', .max = 'g' });
	2193	try testing.expectEqual(minMax(u8, "bcdefga"), .{ .min = 'a', .max = 'g' });
	2194	try testing.expectEqual(minMax(u8, "a"), .{ .min = 'a', .max = 'a' });
	2195	}
	2196
2177	2197	/// Returns the index of the smallest number in a slice. O(n).
2178	2198	/// `slice` must not be empty.
2179	2199	pub fn indexOfMin(comptime T: type, slice: []const T) usize {
...	...	@@ -2216,6 +2236,34 @@ test "mem.indexOfMax" {
2216	2236	try testing.expectEqual(indexOfMax(u8, "a"), 0);
2217	2237	}
2218	2238
	2239	/// Finds the indices of the smallest and largest number in a slice. O(n).
	2240	/// Returns an anonymous struct with the fields `index_min` and `index_max`.
	2241	/// `slice` must not be empty.
	2242	pub fn indexOfMinMax(comptime T: type, slice: []const T) struct { index_min: usize, index_max: usize } {
	2243	assert(slice.len > 0);
	2244	var minVal = slice[0];
	2245	var maxVal = slice[0];
	2246	var minIdx: usize = 0;
	2247	var maxIdx: usize = 0;
	2248	for (slice[1..]) \|item, i\| {
	2249	if (item < minVal) {
	2250	minVal = item;
	2251	minIdx = i + 1;
	2252	}
	2253	if (item > maxVal) {
	2254	maxVal = item;
	2255	maxIdx = i + 1;
	2256	}
	2257	}
	2258	return .{ .index_min = minIdx, .index_max = maxIdx };
	2259	}
	2260
	2261	test "mem.indexOfMinMax" {
	2262	try testing.expectEqual(indexOfMinMax(u8, "abcdefg"), .{ .index_min = 0, .index_max = 6 });
	2263	try testing.expectEqual(indexOfMinMax(u8, "gabcdef"), .{ .index_min = 1, .index_max = 0 });
	2264	try testing.expectEqual(indexOfMinMax(u8, "a"), .{ .index_min = 0, .index_max = 0 });
	2265	}
	2266
2219	2267	pub fn swap(comptime T: type, a: T, b: T) void {
2220	2268	const tmp = a.*;
2221	2269	a.* = b.*;