Create validate-ip-address.cpp

Author: kamyu104

C++/validate-ip-address.cpp

@@ -0,0 +1,62 @@
+// Time:  O(1)
+// Space: O(1)
+
+class Solution {
+public:
+    string validIPAddress(string IP) {
+    	stringstream ss(IP);
+    	string block;
+    	if (IP.substr(0, 4).find('.') != string::npos) {
+    	    for (int i = 0; i < 4; ++i) {
+        		if (!getline(ss, block, '.') || !isValidIPv4Block(block)) {
+        	   	    return "Neither";
+        		}
+    	    }
+    	    if (ss.eof()) {
+    	        return "IPv4";
+    	    }
+    	} else if (IP.substr(0, 5).find(':') != string::npos) {
+    	    for (int i = 0; i < 8; ++i) {
+        		if (!getline(ss, block, ':') || !isValidIPv6Block(block)) {
+        		    return "Neither";
+        		}
+    	    }
+    	    if (ss.eof()) {
+    	        return "IPv6";
+    	    }
+    	}
+    
+    	return "Neither";
+    }
+
+private:
+    bool isValidIPv4Block(const string& block) {
+    	int num = 0;
+    	if (block.size() > 0 && block.size() <= 3) {
+    	    for (int i = 0; i < block.size(); ++i) {
+    	        char c = block[i];
+    	        if (!isalnum(c) || (i == 0 && c == '0' && block.size() > 1)) {
+    	            return false;
+    	        } else {
+        		    num *= 10;
+        		    num += c - '0';
+    	        }
+    	    }
+    	    return num <= 255;
+    	}
+    	return false;
+    }
+    
+    bool isValidIPv6Block(const string& block) {
+    	if (block.size() > 0 && block.size() <= 4) {
+    	    for (int i = 0; i < block.size(); ++i) {
+    	        char c = block[i];
+    	        if (!isxdigit(c)) {
+    	    	    return false;
+    	        }
+    	    }
+    	    return true;
+    	}
+    	return false;
+    }
+};