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std.mem: Add functions to find the index of the mimimum/maximum value in a slice.

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This commit is contained in:
Mikhail Popov 2021-10-08 00:37:50 +02:00 committed by Veikka Tuominen
parent 6d1b1374f7
commit dddbd2f511
1 changed files with 50 additions and 2 deletions
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52
lib/std/mem.zig
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@ -2143,6 +2143,7 @@ fn testWriteIntImpl() !void {
/// Returns the smallest number in a slice. O(n).
/// `slice` must not be empty.
pub fn min(comptime T: type, slice: []const T) T {
assert(slice.len > 0);
var best = slice[0];
for (slice[1..]) |item| {
best = math.min(best, item);
@ -2151,12 +2152,15 @@ pub fn min(comptime T: type, slice: []const T) T {
}
test "mem.min" {
try testing.expect(min(u8, "abcdefg") == 'a');
try testing.expectEqual(min(u8, "abcdefg"), 'a');
try testing.expectEqual(min(u8, "bcdefga"), 'a');
try testing.expectEqual(min(u8, "a"), 'a');
}
/// Returns the largest number in a slice. O(n).
/// `slice` must not be empty.
pub fn max(comptime T: type, slice: []const T) T {
assert(slice.len > 0);
var best = slice[0];
for (slice[1..]) |item| {
best = math.max(best, item);
@ -2165,7 +2169,51 @@ pub fn max(comptime T: type, slice: []const T) T {
}
test "mem.max" {
try testing.expect(max(u8, "abcdefg") == 'g');
try testing.expectEqual(max(u8, "abcdefg"), 'g');
try testing.expectEqual(max(u8, "gabcdef"), 'g');
try testing.expectEqual(max(u8, "g"), 'g');
}
/// Returns the index of the smallest number in a slice. O(n).
/// `slice` must not be empty.
pub fn indexOfMin(comptime T: type, slice: []const T) usize {
assert(slice.len > 0);
var best = slice[0];
var index: usize = 0;
for (slice[1..]) |item, i| {
if (item < best) {
best = item;
index = i + 1;
}
}
return index;
}
test "mem.indexOfMin" {
try testing.expectEqual(indexOfMin(u8, "abcdefg"), 0);
try testing.expectEqual(indexOfMin(u8, "bcdefga"), 6);
try testing.expectEqual(indexOfMin(u8, "a"), 0);
}
/// Returns the index of the largest number in a slice. O(n).
/// `slice` must not be empty.
pub fn indexOfMax(comptime T: type, slice: []const T) usize {
assert(slice.len > 0);
var best = slice[0];
var index: usize = 0;
for (slice[1..]) |item, i| {
if (item > best) {
best = item;
index = i + 1;
}
}
return index;
}
test "mem.indexOfMax" {
try testing.expectEqual(indexOfMax(u8, "abcdefg"), 6);
try testing.expectEqual(indexOfMax(u8, "gabcdef"), 0);
try testing.expectEqual(indexOfMax(u8, "a"), 0);
}
pub fn swap(comptime T: type, a: *T, b: *T) void {