Add leetcode 318

LeetCode-CN/318.cpp

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    int maxProduct(vector<string>& words) {
+        const int N = words.size();
+        vector<int32_t> mark;
+        for (auto& s : words) {
+            int32_t m = 0;
+            for (auto& c : s) {
+                m |= 1 << (c - 'a');
+            }
+            mark.push_back(m);
+        }
+
+        size_t ret = 0;
+        for (int i = 0; i < N; i++)
+        {
+            for (int j = i + 1; j < N; j++)
+            {
+                if (!(mark[i] & mark[j])) {
+                    ret = max(ret, words[i].size() * words[j].size());
+                }
+            }
+        }
+        return ret;
+    }
+};