const std = @import("std");
const print = std.debug.warn;

fn p1() void {
    var i: usize = 0;
    var sum: usize = 0;

    while (i < 1000) : (i += 1) {
        if (i % 3 == 0) {
            sum += i;
        } else if (i % 5 == 0) {
            sum += i;
        }
    }

    std.debug.warn("{}\n", .{sum});
}

fn p2() void {
    const size: usize = 35;
    var array: [size]usize = undefined;
    for (array) |_, i| {
        array[i] = 0;
    }
    array[0] = 1;
    array[1] = 2;

    var i: usize = 2;
    while (i < size) : (i += 1) {
        array[i] = array[i - 1] + array[i - 2];
    }

    i = 0;
    var sum: usize = 0;
    while (array[i] < 4_000_000) : (i += 1) {
        if (array[i] % 2 == 0)
            sum += array[i];
    }

    std.debug.warn("{}\n", .{sum});
}

fn is_prime(k: usize) bool {
    var i: usize = 2;
    var divided: bool = false;
    while (i < k) : (i += 1) {
        if (k % i == 0) {
            divided = true;
            break;
        }
    }
    return !divided;
}

fn p3() void {
    const size: usize = 5000;
    var primes: [size]usize = undefined;

    var i: usize = 1;
    var j: usize = 0;
    while (j < size) : (i += 1) {
        if (is_prime(i)) {
            primes[j] = i;
            j += 1;
        }
    }

    const n: usize = 600851475143;
    //const n: usize = 13195;
    var biggest: usize = 0;
    for (primes) |prime| {
        if (n % prime == 0) {
            biggest = prime;
        }
    }

    std.debug.warn("{}\n", .{biggest});
}

fn p4() !void {
    var i: usize = 0;
    var j: usize = 0;
    var str: [6]u8 = undefined;
    var largest: usize = 0;
    while (i < 1000) : (i += 1) {
        j = 0;
        while (j < 1000) : (j += 1) {
            _ = try std.fmt.bufPrint(&str, "{}", .{i * j});
            if (i * j > largest and
                str[0] == str[5] and
                str[1] == str[4] and
                str[2] == str[3])
            {
                largest = i * j;
            }
        }
    }
    print("{}\n", .{largest});
}

fn p5() void {
    var num: usize = 20;
    var i: usize = 1;
    var j: usize = 0;
    var found: bool = false;

    while (i < 1_500_000_000) : (i += 1) {
        j = num;

        found = false;
        while (j != 0) : (j -= 1) {
            if (i % j != 0) {
                found = true;
            }
        }

        if (!found) {
            print("{}\n", .{i});
            break;
        }
    }
}

fn p6() void {
    var sum_0: usize = 0;
    var sum_1: usize = 0;

    var i: usize = 1;
    while (i <= 100) : (i += 1) {
        sum_0 += i * i;
        sum_1 += i;
    }
    sum_1 *= sum_1;

    print("{}\n", .{sum_1 - sum_0});
}

fn p7() void {
    const size: usize = 10_002;
    var primes: [size]usize = undefined;

    var i: usize = 1;
    var j: usize = 0;
    while (j < size) : (i += 1) {
        if (is_prime(i)) {
            primes[j] = i;
            j += 1;
        }
    }
    print("{}\n", .{primes[size - 1]});
}

fn p8() void {}

pub fn main() !void {
    //p1();
    //p2();
    //p3();
    //_ = try p4();
    //p5();
    //p6();
    //p7();
    p8();
}