Added: problem "Word Break"

Author: nibblerenush

problems/Word Break/main.cpp

@@ -0,0 +1,52 @@
+#include <algorithm>
+#include <cmath>
+#include <iostream>
+#include <limits>
+#include <map>
+#include <numeric>
+#include <queue>
+#include <set>
+#include <stack>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+using namespace std;
+
+class Solution {
+public:
+  bool wordBreak(string s, vector<string>& wordDict) {
+    move(wordDict.begin(), wordDict.end(), inserter(word_set, word_set.begin()));
+    return backtrack(s, 0);
+  }
+
+private:
+  bool backtrack(const string& s, int begin) {
+    if (begin >= (int)s.length()) {
+      return true;
+    }
+    
+    if (memorization.count(begin)) {
+      return false;
+    }
+    
+    for (int i = begin; i < (int)s.length(); ++i) {
+      string substr = s.substr(begin, i - begin + 1);
+      if (word_set.count(substr) && backtrack(s, i + 1)) {
+        return true;
+      }
+    }
+    
+    memorization.insert(begin);
+    return false;
+  }
+
+private:
+  unordered_set<string> word_set;
+  unordered_set<int> memorization;
+};
+
+int main() {
+  return 0;
+}