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const std = @import("std");
const print = std.debug.print;
const assert = std.debug.assert;
const ArrayList = std.ArrayList;
const HashMap = std.HashMap;
const mem = std.mem;
const fin = mem.trim(u8, @embedFile("./input.txt"), &std.ascii.whitespace);
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
const allocator = gpa.allocator();
fn evalutate(rd: i64, rt: i64) u64 {
var timesBeat: u64 = 0;
for (1..@bitCast(rt + 1)) |tt| {
const t: i64 = @bitCast(tt);
const d = t * rt - t * t;
if (d > rd) {
timesBeat += 1;
}
}
assert(timesBeat != 0);
return timesBeat;
}
pub fn part1(recTimes: []const i64, recDists: []const i64) void {
var ans: u64 = 1;
for (recDists, recTimes) |rd, rt| {
ans *= evalutate(rd, rt);
}
print("{d}\n", .{ans});
}
pub fn part2(recTimes: []const []const u8, recDists: []const []const u8) void {
const rtStr = mem.concat(allocator, u8, recTimes) catch unreachable;
const rdStr = mem.concat(allocator, u8, recDists) catch unreachable;
defer {
allocator.free(rtStr);
allocator.free(rdStr);
}
const rt = std.fmt.parseInt(i64, rtStr, 10) catch unreachable;
const rd = std.fmt.parseInt(i64, rdStr, 10) catch unreachable;
const ans = evalutate(rd, rt);
print("{d}\n", .{ans});
}
pub fn main() !void {
var recTimes = ArrayList(i64).init(allocator);
var recDists = ArrayList(i64).init(allocator);
var recTimesStr = ArrayList([]const u8).init(allocator);
var recDistsStr = ArrayList([]const u8).init(allocator);
defer {
recTimes.deinit();
recDists.deinit();
recTimesStr.deinit();
recDistsStr.deinit();
}
var splitLines = mem.splitScalar(u8, fin, '\n');
var timesText = mem.splitScalar(u8, splitLines.next().?, ' ');
var distsText = mem.splitScalar(u8, splitLines.next().?, ' ');
_ = timesText.next().?;
_ = distsText.next().?;
while (timesText.next()) |time| {
try recTimes.append(std.fmt.parseInt(i64, time, 10) catch continue);
try recTimesStr.append(time);
}
while (distsText.next()) |dist| {
try recDists.append(std.fmt.parseInt(i64, dist, 10) catch continue);
try recDistsStr.append(dist);
}
part1(recTimes.items, recDists.items);
part2(recTimesStr.items, recDistsStr.items);
}
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