const std = @import("std");

const first = 171309;
const last  = 643603;

// - [x] It is a six-digit number (implied)
// - [x] The value is within the range given in your puzzle input (implied)
// - [x] Two adjacent digits are the same (like 22 in 122345).
// - [x] Going from left to right, the digits never decrease; they only ever increase or stay the same (like 111123 or 135679).

fn tests1(num: i32) anyerror!bool {
    var buf: [6]u8 = undefined;
    var numStr = try std.fmt.bufPrint(&buf, "{}", num);

    if (numStr[0] > numStr[1] or
        numStr[1] > numStr[2] or
        numStr[2] > numStr[3] or
        numStr[3] > numStr[4] or
        numStr[4] > numStr[5]
    ) return false;

    return
        numStr[0] == numStr[1] or
        numStr[1] == numStr[2] or
        numStr[2] == numStr[3] or
        numStr[3] == numStr[4] or
        numStr[4] == numStr[5];
}

pub fn main() anyerror!void {
    var count: i32 = 0;
    var i: i32 = first;

    while (i <= last) : (i+=1) {
        if (try tests1(i)) {
            //std.debug.warn("Match: {}\n", i);
            count+=1;
        }
    }

    std.debug.warn("Part 1: matches: {}\n", count);
}