feat(src): add 393-validUtf8

Author: kwu130

src/393-validUtf8.cpp

@@ -0,0 +1,54 @@
+//
+// Created by 1412 on 2026/4/13.
+//
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    bool validUtf8(vector<int>& data) {
+        for (size_t i = 0; i < data.size(); ++i) {
+            if (data[i] >> 7 == 0b0) {
+                continue;
+            }
+            if (data[i] >> 5 == 0b110) {
+                if (i + 1 < data.size() && data[i + 1] >> 6 == 0b10) {
+                    i++;
+                    continue;
+                }
+            }
+            if (data[i] >> 4 == 0b1110) {
+                if (i + 2 < data.size() && data[i + 1] >> 6 == 0b10 && data[i + 2] >> 6 == 0b10) {
+                    i += 2;
+                    continue;
+                }
+            }
+            if (data[i] >> 3 == 0b11110) {
+                if (i + 3 < data.size() && data[i + 1] >> 6 == 0b10 && data[i + 2] >> 6 == 0b10 &&
+                    data[i + 3] >> 6 == 0b10) {
+                    i += 3;
+                    continue;
+                }
+            }
+            return false;
+        }
+        return true;
+    }
+};
+
+void test() {
+    Solution s;
+    vector<int> data = {197, 130, 1};
+    assert(s.validUtf8(data) == true);
+    data = {235, 140, 4};
+    assert(s.validUtf8(data) == false);
+    data = {237};
+    assert(s.validUtf8(data) == false);
+}
+
+int main() {
+    test();
+    return 0;
+}