64 lines
1.7 KiB
Zig
64 lines
1.7 KiB
Zig
const std = @import("std");
|
|
const heap = std.heap;
|
|
const math = std.math;
|
|
const expect = std.testing.expect;
|
|
|
|
pub fn main() !void {
|
|
var gpa = heap.GeneralPurposeAllocator(.{}){};
|
|
var arena = heap.ArenaAllocator.init(gpa.allocator());
|
|
defer arena.deinit();
|
|
|
|
var n = try subsequence(arena.allocator(), "fish", "fosh");
|
|
std.debug.print("{d}\n", .{n});
|
|
}
|
|
|
|
fn subsequence(allocator: std.mem.Allocator, a: []const u8, b: []const u8) !u32 {
|
|
var grid = try allocator.alloc([]u32, a.len + 1);
|
|
|
|
for (grid) |*row| {
|
|
row.* = try allocator.alloc(u32, b.len + 1);
|
|
for (row.*) |*cell| {
|
|
cell.* = 0;
|
|
}
|
|
}
|
|
|
|
var i: usize = 1;
|
|
while (i <= a.len) : (i += 1) {
|
|
var j: usize = 1;
|
|
while (j <= b.len) : (j += 1) {
|
|
if (a[i - 1] == b[j - 1]) {
|
|
grid[i][j] = grid[i - 1][j - 1] + 1;
|
|
} else {
|
|
grid[i][j] = math.max(grid[i][j - 1], grid[i - 1][j]);
|
|
}
|
|
}
|
|
}
|
|
|
|
return grid[a.len][b.len];
|
|
}
|
|
|
|
test "subsequence" {
|
|
var tests = [_]struct {
|
|
a: []const u8,
|
|
b: []const u8,
|
|
exp: u32,
|
|
}{
|
|
.{ .a = "abc", .b = "abcd", .exp = 3 },
|
|
.{ .a = "pera", .b = "mela", .exp = 2 },
|
|
.{ .a = "banana", .b = "kiwi", .exp = 0 },
|
|
};
|
|
|
|
for (tests) |t| {
|
|
var gpa = heap.GeneralPurposeAllocator(.{}){};
|
|
var arena = heap.ArenaAllocator.init(gpa.allocator());
|
|
defer {
|
|
arena.deinit();
|
|
const leaked = gpa.deinit();
|
|
if (leaked) std.testing.expect(false) catch @panic("TEST FAIL"); //fail test; can't try in defer as defer is executed after we return
|
|
}
|
|
|
|
var n = try subsequence(arena.allocator(), t.a, t.b);
|
|
try expect(n == t.exp);
|
|
}
|
|
}
|