Longest Increasing subsequence using binary search most optimal approach (Modified)

search/Longest_Increasing_Subsequence_using_binary_search.cpp

@@ -0,0 +1,52 @@
+#include <cassert>   /// for std::assert
+#include <iostream>  /// for IO operations
+#include <vector>    /// for std::vector
+#include <algorithm> /// for std::lower_bound
+
+/**
+ * @brief Function to find the length of the Longest Increasing Subsequence (LIS)
+ * using Binary Search
+ * @param nums The input vector of integers
+ * @return The length of the longest increasing subsequence
+ */
+int longest_increasing_subsequence_using_binary_search(std::vector<int>& nums) {
+    if (nums.empty()) return 0;
+
+    std::vector<int> ans;
+    ans.push_back(nums[0]);
+    for (int i = 1; i < nums.size(); i++) {
+        if (nums[i] > ans.back()) {
+            ans.push_back(nums[i]);
+        } else {
+            int idx = std::lower_bound(ans.begin(), ans.end(), nums[i]) - ans.begin();
+            ans[idx] = nums[i];
+        }
+    }
+    return ans.size();
+}
+
+/**
+ * @brief Test cases for Longest Increasing Subsequence function
+ * @returns void
+ */
+static void tests() {
+    std::vector<int> arr = {10, 9, 2, 5, 3, 7, 101, 18};
+    assert(longest_increasing_subsequence_using_binary_search(arr) == 4);
+
+    std::vector<int> arr2 = {0, 1, 0, 3, 2, 3};
+    assert(longest_increasing_subsequence_using_binary_search(arr2) == 4);
+
+    std::vector<int> arr3 = {7, 7, 7, 7, 7, 7, 7};
+    assert(longest_increasing_subsequence_using_binary_search(arr3) == 1);
+
+    std::cout << "All tests have successfully passed!\n";
+}
+
+/**
+ * @brief Main function to run tests
+ * @returns 0 on exit
+ */
+int main() {
+    tests();
+    return 0;
+}