Create longest-chunked-palindrome-decomposition.cpp

Author: kamyu104

C++/longest-chunked-palindrome-decomposition.cpp

@@ -0,0 +1,43 @@
+// Time:  O(n)
+// Space: O(1)
+
+// Rabin-Karp Algorithm
+class Solution {
+public:
+    Solution() : pow_(N_ + 1, 1) {
+        for (int i = 1; i < pow_.size(); ++i) {
+            pow_[i] = (pow_[i - 1] * D_) % MOD_;
+        }
+    }
+
+    int longestDecomposition(string text) {
+        int result = 0;
+        int l = 0, left = 0, right = 0;
+        for (int i = 0; i < text.length(); ++i) {
+            ++l;
+            left = (pow_[1] * left + (text[i] - 'a')) % MOD_;
+            right = (pow_[l - 1] * (text[text.length() - 1 - i] - 'a') + right) % MOD_;
+            if (left == right &&
+                compare(text, l, i - l + 1, text.length() - 1 - i)) {
+                ++result;
+                l = 0, left = 0, right = 0;
+            }
+        }
+        return result;
+    }
+
+private:
+    bool compare(const string& text, size_t l, int s1, int s2) {
+        for (int i = 0; i < l; ++i) {
+            if (text[s1 + i] != text[s2 + i]) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    vector<uint64_t> pow_;
+    static const int N_ = 1000;
+    static const uint64_t MOD_ = 1e9 + 7;
+    static const uint64_t D_ = 26;
+};