Implement split-a-string-in-balanced-strings

https://leetcode.com/problems/split-a-string-in-balanced-strings
Fixes #224

time: 0ms
time-rank: 100%
time-complexity: O(N)

space: 6.5MB
space-rank: 26.98%
space-complexity: O(1)

Author: cfriedt

split-a-string-in-balanced-strings-test.cpp

@@ -0,0 +1,73 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2018 Christopher Friedt
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <gtest/gtest.h>
+
+#include "split-a-string-in-balanced-strings.cpp"
+
+TEST(SplitAStringInBalancedStrings, Test_RLRRLLRLRL) {
+  string input = "RLRRLLRLRL";
+  vector<string> expected_vs = {
+      "RL",
+      "RRLL",
+      "RL",
+      "RL",
+  };
+  int expected_int = expected_vs.size();
+  int actual_int = Solution().balancedStringSplit(input);
+  EXPECT_EQ(actual_int, expected_int);
+}
+
+TEST(SplitAStringInBalancedStrings, Test_RLLLLRRRLR) {
+  string input = "RLLLLRRRLR";
+  vector<string> expected_vs = {
+      "RL",
+      "LLLRRR",
+      "LR",
+  };
+  int expected_int = expected_vs.size();
+  int actual_int = Solution().balancedStringSplit(input);
+  EXPECT_EQ(actual_int, expected_int);
+}
+
+TEST(SplitAStringInBalancedStrings, Test_LLLLRRRR) {
+  string input = "LLLLRRRR";
+  vector<string> expected_vs = {
+      "LLLLRRRR",
+  };
+  int expected_int = expected_vs.size();
+  int actual_int = Solution().balancedStringSplit(input);
+  EXPECT_EQ(actual_int, expected_int);
+}
+
+TEST(SplitAStringInBalancedStrings, Test_RLRRRLLRLL) {
+  string input = "RLRRRLLRLL";
+  vector<string> expected_vs = {
+      "RL",
+      "RRRLLRLL",
+  };
+  int expected_int = expected_vs.size();
+  int actual_int = Solution().balancedStringSplit(input);
+  EXPECT_EQ(actual_int, expected_int);
+}

split-a-string-in-balanced-strings.cpp

@@ -0,0 +1,68 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2018 Christopher Friedt
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <string>
+
+using namespace std;
+
+class Solution {
+public:
+  // https://leetcode.com/problems/split-a-string-in-balanced-strings/
+
+  int balancedStringSplit(string s) {
+
+    /*
+     * ex
+     * RLRRLLRLRL
+     *
+     * p1 p2 c1 c2 balance npairs
+     * 0  1  R  L  0       1
+     * 2  3  R  R  -2      1
+     * 2  4  R  L  -1      1
+     * 2  5  R  L  0       2
+     * 6  7  R  L  0       3
+     * 8  9  R  L  0       4
+     */
+
+    int r = 0;
+    int balance = 0;
+    for (size_t p1 = 0, p2 = 1, N = s.size(); p1 + 1 < N && p2 < N;) {
+      if ((0 == p1 && 1 == p2) || 0 == balance) {
+        balance += (s[p1] == 'R') ? -1 : 1;
+      }
+
+      balance += (s[p2] == 'R') ? -1 : 1;
+
+      if (0 == balance) {
+        ++r;
+        p1 = p2 + 1;
+        p2 += 2;
+      } else {
+        ++p2;
+      }
+    }
+
+    return r;
+  }
+};