add sol

leetcode/93.RestoreIPAddresses/restoreIPAddresses.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+func restoreIPAddresses(s string) []string {
+	result := []string{}
+	segments := make([]string, 4)
+
+	var backtrack func(start, segmentNum int)
+	backtrack = func(start, segmentNum int) {
+		// If we've got 4 segments and used all characters in the string, it's a valid IP address
+		if segmentNum == 4 && start == len(s) {
+			ip := strings.Join(segments, ".")
+			result = append(result, ip)
+			return
+		}
+
+		// If we've got 4 segments but not all characters, it's not valid
+		if segmentNum == 4 || start == len(s) {
+			return
+		}
+
+		if s[start] == '0' {
+			segments[segmentNum] = "0"
+			backtrack(start+1, segmentNum+1)
+		}
+
+		addr := 0
+		for i := start; i < len(s); i++ {
+			addr = addr*10 + int(s[i]-'0')
+			if addr > 0 && addr <= 255 {
+				segments[segmentNum] = strconv.Itoa(addr)
+				backtrack(i+1, segmentNum+1)
+			} else {
+				break
+			}
+		}
+	}
+
+	backtrack(0, 0)
+	return result
+}
+
+func main() {
+	ip := "25525511135"
+	fmt.Println(restoreIPAddresses(ip))
+}