From 0225aaf204fb3aed83bbb3514a144545b0bcffbf Mon Sep 17 00:00:00 2001
From: Manish <manish@radii.dev>
Date: Fri, 10 Mar 2023 21:07:04 +1100
Subject: [PATCH] Design Pattern 11 | Problem: Permutation in String

---
 11_permutations_in_string.cpp | 40 +++++++++++++++++++++++++++++++++++
 CMakeLists.txt                |  4 +++-
 2 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 11_permutations_in_string.cpp

diff --git a/11_permutations_in_string.cpp b/11_permutations_in_string.cpp
new file mode 100644
index 0000000..b218c61
--- /dev/null
+++ b/11_permutations_in_string.cpp
@@ -0,0 +1,40 @@
+/* Problem: https://leetcode.com/problems/permutation-in-string/ */
+
+#include <iostream>
+#include <unordered_map>
+
+bool solution(const std::string s1, const std::string s2) {
+  if (s1.length() > s2.length())
+    return false;
+  std::size_t s1_len = s1.length();
+  std::unordered_map<char, std::size_t> s1_count, s2_substr_count;
+  for (const char c : s1)
+    s1_count[c]++;
+  for (auto c = s2.cbegin(), e = s2.cbegin() + s1.length(); c != e; c++) {
+    s2_substr_count[*c]++;
+  }
+  for (std::size_t i = s1_len, upto = s2.length(); i < upto; i++) {
+    bool match_found = true;
+    for (auto const [character, count] : s1_count) {
+      if (s2_substr_count[character] != count) {
+        match_found = false;
+        break;
+      }
+    }
+    if (match_found)
+      return true;
+    s2_substr_count[s2[i - s1_len]]--;
+    s2_substr_count[s2[i]]++;
+  }
+  for (auto const [character, count] : s1_count) {
+    if (s2_substr_count[character] != count)
+      return false;
+  }
+  return true;
+}
+
+int main() {
+  std::cout << solution("ab", "eidbaooo") << '\n'
+            << solution("ab", "eidboaoo") << '\n'
+            << solution("dinitrophenylhydrazine", "dimethylhydrazine") << '\n';
+}
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 80f6d29..eaa1c32 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,4 +25,6 @@ add_executable(9_path_sum_iii 9_path_sum_iii.cpp)
 
 add_executable(10_find_the_median_of_a_number_stream 10_find_the_median_of_a_number_stream.cpp)
 
-add_executable(11_letter_case_permutation 11_letter_case_permutation.cpp)
\ No newline at end of file
+add_executable(11_letter_case_permutation 11_letter_case_permutation.cpp)
+
+add_executable(11_permutations_in_string 11_permutations_in_string.cpp)
\ No newline at end of file