move to 2020 fodler

2020/solutions/2/README.md

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+# 2
+
+For the first we can simply count the occurrences and see if they are between the accepted values.
+Just some simple parsing.
+
+The second one is similar, but we can be more efficient if we XOR the first and second position.
+
+<details>
+  <summary>Solutions</summary>
+  <ol>
+    <li>548</li>
+    <li>502</li>
+  </ol>
+</details>

2020/solutions/2/go/main.go

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+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"strings"
+)
+
+type sRow struct {
+	min, max       int
+	char, password string
+}
+
+func parse(data []byte) []sRow {
+	parsed := []sRow{}
+	for _, row := range strings.Split(strings.TrimSpace(string(data)), "\n") {
+		s0 := strings.Split(row, ":")
+		rule := strings.TrimSpace(s0[0])
+		password := strings.TrimSpace(s0[1])
+		s1 := strings.Split(rule, " ")
+		minMax := strings.TrimSpace(s1[0])
+		char := strings.TrimSpace(s1[1])
+		s2 := strings.Split(minMax, "-")
+		min, _ := strconv.Atoi(strings.TrimSpace(s2[0]))
+		max, _ := strconv.Atoi(strings.TrimSpace(s2[1]))
+
+		r := sRow{
+			min:      min,
+			max:      max,
+			char:     char,
+			password: password,
+		}
+		parsed = append(parsed, r)
+	}
+	return parsed
+}
+
+func validSimple(rows []sRow) int {
+	valid := 0
+	for _, row := range rows {
+		count := strings.Count(row.password, row.char)
+		if row.min <= count && count <= row.max {
+			valid++
+		}
+	}
+	return valid
+}
+
+func validComplex(rows []sRow) int {
+	valid := 0
+	for _, row := range rows {
+		l := len(row.password)
+		min := row.min - 1
+		max := row.max - 1
+		if min >= l || max >= l {
+			continue
+		}
+		r := []rune(row.password)
+		a := string(r[min]) == row.char
+		b := string(r[max]) == row.char
+		if a != b {
+			valid++
+		}
+	}
+
+	return valid
+}
+
+func main() {
+	data, _ := ioutil.ReadFile("./solutions/2/data.txt")
+	rows := parse(data)
+	simple := validSimple(rows)
+	fmt.Println(simple)
+	complex := validComplex(rows)
+	fmt.Println(complex)
+}

2020/solutions/2/python/main.py

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+from os.path import join, dirname
+
+
+def checkRow(row: str, alternative=False) -> bool:
+    rule, password = map(lambda s: s.strip(), row.split(':'))
+    amount, char = rule.split(' ')
+    minimum, maximum = map(int, amount.split('-'))
+    if alternative:
+        return (password[minimum - 1] == char) ^ (password[maximum - 1] == char)
+    else:
+        occurrences = password.count(char)
+        return minimum <= occurrences <= maximum
+
+
+data = join(dirname(__file__), '../data.txt')
+with open(data) as f:
+    valid = 0
+    valid_alt = 0
+    rows = list(f.read().strip().split('\n'))
+    for row in rows:
+        if(checkRow(row)):
+            valid += 1
+        if(checkRow(row, alternative=True)):
+            valid_alt += 1
+    print(f'Found {valid} valid passwords.')
+    print('Policy changed...')
+    print(f'Found {valid_alt} valid passwords.')