feat(): 模拟

Author: descire

string/468/solution1.js

@@ -0,0 +1,48 @@
+/**
+ * 时间复杂度：O(n)
+ * 空间复杂度：O(1)
+ */
+const isDigit = (str) => !Number.isNaN(Number.parseInt(str, 10));
+
+const validIPAddress = queryIP => {
+    if (queryIP.indexOf('.') >= 0) {
+        let last = -1;
+        for (let i = 0; i < 4; i++) {
+            const current = i === 3 ? queryIP.length : queryIP.indexOf('.', last + 1);
+
+            if (current < 0 || current - last  - 1 < 1 || current - last - 1 > 3) {
+                return 'Neither';
+            }
+
+            let address = 0;
+            for (let j = last + 1; j < current; j++) {
+                if (!isDigit(queryIP[j])) {
+                    return 'Neither';
+                }
+                address = address * 10 + (queryIP[j].charCodeAt() - '0'.charCodeAt());
+            }
+
+            if (address > 255 || (address > 0 && queryIP[last + 1].charCodeAt() === '0'.charCodeAt()) || (address === 0 && current - last - 1 > 1)) {
+                return 'Neither';
+            }
+            last = current;
+        }
+        return 'IPv4';
+    }
+
+    let last = -1;
+    for (let i = 0; i < 8; i++) {
+        const current = (i === 7 ? queryIP.length : queryIP.indexOf(':', last + 1));
+        if (current < 0 || current - last - 1 < 1 || current - last - 1 > 4) {
+            return "Neither";
+        }
+        for (let j = last + 1; j < current; ++j) {
+            if (!isDigit(queryIP[j]) && !('a' <= queryIP[j].toLowerCase() && queryIP[j].toLowerCase() <= 'f')) {
+                return "Neither";
+            }
+        }
+        last = current;
+    }
+
+    return 'IPv6';
+}