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Add std.sort.argMax and std.sort.argMin

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This commit is contained in:
Robin Voetter 2019-12-04 18:20:55 +01:00
parent 0159fa284a
commit 841a37ab59
1 changed files with 42 additions and 8 deletions
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50
lib/std/sort.zig
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@ -1189,19 +1189,36 @@ fn fuzzTest(rng: *std.rand.Random) void {
}
}
pub fn min(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) ?T {
pub fn argMin(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) ?usize {
if (items.len == 0) {
return null;
}
var i: usize = 0;
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;
}
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" {
@ -1214,19 +1231,36 @@ test "std.sort.min" {
testing.expectEqual(@as(?i32, 7), min(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 {
pub fn argMax(comptime T: type, items: []const T, lessThan: fn (lhs: T, rhs: T) bool) ?usize {
if (items.len == 0) {
return null;
}
var i: usize = 0;
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" {