Added solutions for 10th day : syntax scoring

1 files changed, 86 insertions, 0 deletions

diff --git a/2021/10/second.go b/2021/10/second.go
new file mode 100644
index 0000000..69bd104
--- /dev/null
+++ b/2021/10/second.go
@@ -0,0 +1,86 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"sort"
+)
+
+type stack []byte
+
+func (s *stack) clear() {
+	*s = make(stack, 0)
+}
+
+func (s *stack) push(b byte) {
+	*s = append(*s, b)
+}
+
+func (s *stack) pop() *byte {
+	l := len(*s)
+	if l == 0 {
+		return nil
+	} else {
+		elt := (*s)[l-1]
+		*s = (*s)[:l-1]
+		return &elt
+	}
+}
+
+func main() {
+	scores := make([]int, 0)
+	s := make(stack, 0)
+
+	scanner := bufio.NewScanner(os.Stdin)
+out:
+	for scanner.Scan() {
+		line := scanner.Text()
+		s.clear()
+		for i := 0; i < len(line); i++ {
+			c := line[i]
+			if c == '(' || c == '[' || c == '{' || c == '<' {
+				s.push(c)
+				continue
+			}
+			b := s.pop()
+			switch c {
+			case ')':
+				if *b != '(' {
+					continue out
+				}
+			case ']':
+				if *b != '[' {
+					continue out
+				}
+			case '}':
+				if *b != '{' {
+					continue out
+				}
+			case '>':
+				if *b != '<' {
+					continue out
+				}
+			}
+		}
+		score := 0
+		for c := s.pop(); c != nil; c = s.pop() {
+			score *= 5
+			switch *c {
+			case '(':
+				score += 1
+			case '[':
+				score += 2
+			case '{':
+				score += 3
+			case '<':
+				score += 4
+			}
+		}
+		if score != 0 {
+			scores = append(scores, score)
+		}
+	}
+	sort.Ints(scores)
+	fmt.Println(scores[len(scores)/2])
+}