[UPDATED]feat: add activity selection problem

greedy_algorithms/activity_selection.cpp

@@ -0,0 +1,66 @@
+/**
+Problem Statement:
+You are given n activities with their start and finish times. Select the maximum number of activities
+that can be performed by a single person, assuming that a person can only work on a single activity at a time.
+Solution:
+Since the activities are sorted in increasing order of finish time, we chose the activity whose finish time is less than
+all other activities and start time is more than the previous activities finish time. We should sort the activities in
+increasing order of finish time of activities.
+*/
+// The assumption here is input activities will be provided in sorted order of finish time of activities.
+#include <cassert>   /// for assert
+#include <iostream>
+#include <vector>
+
+// Prints a maximum set of activities that can be done by a
+// single person, one at a time.
+std::vector<int> getMaxActivities(std::vector<int> start, std::vector<int> finish, int n)
+{
+    int i, j;
+    std::vector<int> ans;
+
+
+    // Since we greedily start selecting the activities the first activity is always selected
+    i = 0;
+    ans.push_back(i);
+
+    // Considering the rest of the activities
+    for (j = 1; j < n; j++) {
+        // If this activity has start time greater than or
+        // equal to the finish time of previously selected
+        // activity, then select it
+        if (start[j] >= finish[i]) {
+            ans.push_back(j);
+            i = j;
+        }
+    }
+    return ans;
+}
+
+static void tests() {
+    std::vector<int> start = {1, 3, 0, 5, 8, 5};
+    std::vector<int> finish = {2, 4, 6, 7, 9, 9};
+
+    std::vector<int> ans = getMaxActivities(start, finish, start.size());
+    std::vector<int> activities = {0, 1, 6, 4};
+
+    for(int i = 0 ; i < activities.size(); i++){
+        uint64_t activityNumber = ans[i];
+        assert(activityNumber == activities[i]);
+    }
+}
+
+// Driver code
+int main()
+{
+    //tests();
+    std::vector<int> start = {1, 3, 0, 5, 8, 5};
+    std::vector<int> finish = {2, 4, 6, 7, 9, 9};
+    // Function call
+    std::vector<int> ans = getMaxActivities(start, finish, start.size());
+    std::cout << "Following activities are selected" << "\n";
+    for(int x: ans) {
+        std::cout << x <<", ";
+    }
+    return 0;
+}