const input = @embedFile("input3");
const std = @import("std");

pub fn main() !void{


    var counting = [1]usize{0} ** 12;

    var iter = std.mem.tokenize(u8, input, "\n");
    while(iter.next() ) |line| {

        for(line)|c, i|{
            counting[i] += (c -48); //HACK: subtract 48 to go from ascii to bit
        }


        //@popCount(u8,line); // >=3 means 1 is most common bit.
    }


    //
    var gamma:  u12 = 0;
    var epsilon:u12 = 0;
    
    for(counting)|count, i|{

        if(count > 500){
            counting[i] = 1;
        }else{
            counting[i] = 0;
        }
    }


    for(counting)|c, i|{
        if(c == 1) gamma |= @as(u12, 1) << @intCast(u4,i ) ;
    }

    gamma = @bitReverse(u12, gamma);
    epsilon = ~gamma;

    const result: u64 = gamma * @as(u64, epsilon);

    std.debug.print("result: {}", .{result});
}

test "part 1"{


    var counting = [1]usize{0} ** 12;

    var iter = std.mem.tokenize(u8, input, "\n");
    while(iter.next() ) |line| {

        for(line)|c, i|{
            counting[i] += (c -48); //HACK: subtract 48 to go from ascii to bit
        }

    }


    //
    var gamma:  u12 = 0;
    var epsilon:u12 = 0;
    
    for(counting)|count, i|{

        if(count > 500){
            counting[i] = 1;
        }else{
            counting[i] = 0;
        }
    }


    for(counting)|c, i|{
        if(c == 1) gamma |= @as(u12, 1) << @intCast(u4,i ) ;
    }

    gamma = @bitReverse(u12, gamma);
    epsilon = ~gamma;
    const result: u64 = gamma * @as(u64, epsilon);

    std.testing.expect(2648450 == result);
}