Create longest-string-chain.cpp

Author: kamyu104

C++/longest-string-chain.cpp

@@ -0,0 +1,26 @@
+// Time:  O(n * l^2)
+// Space: O(n * l)
+
+class Solution {
+public:
+    int longestStrChain(vector<string>& words) {
+        sort(words.begin(), words.end(),
+             [](const string& a, const string& b) {
+                 return less<int>()(a.length(), b.length());
+             });
+        unordered_map<string, int> dp;
+        for (const auto& w : words) {
+            for (int i = 0; i < w.length(); ++i) {
+                auto tmp = w.substr(0, i);
+                tmp += w.substr(i + 1);
+                dp[w] = max(dp[w], dp[tmp] + 1);
+            }
+        }
+        using pair_type = decltype(dp)::value_type;
+        return max_element(dp.cbegin(), dp.cend(),
+                           [] (const pair_type& a,
+                               const pair_type& b) {
+                               return a.second < b.second;
+                           })->second;
+    }
+};