2020 day 4

2020/4/day4.lua

@@ -0,0 +1,79 @@
+#!/usr/bin/env lua
+
+local passports, current = {}, {}
+for line in io.lines() do
+    if line == "" then
+        table.insert(passports, current)
+        current = {}
+    end
+    for name, value in line:gmatch("(%a+):(%g+)") do
+        current[name] = value
+    end
+end
+table.insert(passports, current)
+
+local function validate_byr(val)
+    val = tonumber(val)
+    return val and val >= 1920 and val <= 2002
+end
+
+local function validate_iyr(val)
+    val = tonumber(val)
+    return val and val >= 2010 and val <= 2020
+end
+
+local function validate_eyr(val)
+    val = tonumber(val)
+    return val and val >= 2020 and val <= 2030
+end
+
+local function validate_hgt(val)
+    local suffix = val:sub(-2)
+    val = tonumber(val:sub(1, -3))
+    if not val then return false end
+    if suffix == "cm" then
+        return val >= 150 and val <= 193
+    elseif suffix == "in" then
+        return val >= 59 and val <= 76
+    else return false end
+end
+
+local function validate_hcl(val)
+    return val and val:match("#%x%x%x%x%x")
+end
+
+local function validate_ecl(val)
+    return ({amb=true, blu=true, brn=true, gry=true, grn=true, hzl=true, oth=true})[val]
+end
+
+local function validate_pid(val)
+    return val and val:match("^%d%d%d%d%d%d%d%d%d$")
+end
+
+local required_fields = {
+    byr=validate_byr,
+    iyr=validate_iyr,
+    eyr=validate_eyr,
+    hgt=validate_hgt,
+    hcl=validate_hcl,
+    ecl=validate_ecl,
+    pid=validate_pid,
+}
+
+local function validate(run_checks)
+    local count = 0
+    for _, passport in ipairs(passports) do
+        local ok = 1
+        for field, validator in pairs(required_fields) do
+            if passport[field] == nil or (run_checks and not validator(passport[field])) then
+                ok = 0
+                break
+            end
+        end
+        count = count + ok
+    end
+    return count
+end
+
+print(validate(false))
+print(validate(true))

README.md

@@ -9,7 +9,7 @@ My solutions to the Advent of Code puzzles.
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