57 lines
1.7 KiB
Zig
57 lines
1.7 KiB
Zig
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const std = @import("std");
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const input = @embedFile("input");
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pub fn main() !void {
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// Put this or it doesn't evaluate all branches
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@setEvalBranchQuota(500000);
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const result = comptime findUniqueCharsIdx(14, input);
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const ares = comptime uintEncode(result, 10, "0123456789") catch unreachable;
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_ = std.os.linux.write(1, &ares, 10);
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}
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fn uintEncode(num: usize, comptime bufflen: usize, comptime charset: []const u8) ![bufflen]u8 {
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// Check if the number is bigger than the maximum possible number
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var pow = comptime std.math.pow(usize, charset.len, bufflen);
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if (num >= pow) unreachable;
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var buff = [_]u8{charset[0]} ** bufflen;
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var num_i: usize = num;
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for (buff) |*pos| {
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pow /= charset.len;
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pos.* = charset[@divTrunc(num_i, pow)];
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num_i %= pow;
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}
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return buff;
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}
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fn findUniqueCharsIdx(_n: usize, string: []const u8) usize {
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for (input) |_, i| {
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const n = _n - 1;
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// Start searching at fourth character
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if (i < n) continue;
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if (i > input.len - n) break;
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const chars: []const u8 = string[i-n..i+1];
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chars: for (chars) |char_1, j| {
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for (chars) |char_2, k| {
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// Don't check the same character, or the ones that we already checked
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if (j <= k) continue;
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//std.debug.print("{c},{c}\n", .{char_1, char_2});
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if (char_1 == char_2) {
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// Don't check anymore
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break :chars;
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}
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}
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} else {
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// If no repeats have been found
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// i is the current character index in the input (i+1 if we count from 1)
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return i + 1;
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}
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}
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return 0;
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}
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