From 65aec17dd9ab80a8d299d73c13d110edc409049c Mon Sep 17 00:00:00 2001
From: Kishorsarswat <kishorsarswat9291@gmail.com>
Date: Thu, 22 Oct 2020 13:22:36 +0530
Subject: [PATCH] added mergingMeetings.cpp,multiolicationOf3Integers.cpp

---
 .../cpp/multiplication of 3 intigers.cpp      |  70 +++++++++++
 .../merging meetings/cpp/meetings.cpp         | 117 ++++++++++++++++++
 2 files changed, 187 insertions(+)
 create mode 100644 Greedy Algorithms/maximising multiplication of 3 intigers/cpp/multiplication of 3 intigers.cpp
 create mode 100644 Greedy Algorithms/merging meetings/cpp/meetings.cpp

diff --git a/Greedy Algorithms/maximising multiplication of 3 intigers/cpp/multiplication of 3 intigers.cpp b/Greedy Algorithms/maximising multiplication of 3 intigers/cpp/multiplication of 3 intigers.cpp
new file mode 100644
index 000000000..631123fc1
--- /dev/null
+++ b/Greedy Algorithms/maximising multiplication of 3 intigers/cpp/multiplication of 3 intigers.cpp	
@@ -0,0 +1,70 @@
+//problem
+//Given a vector of integers, find the highest product you can get from three of the integers.
+//The input vectorOfInts will always have at least three integers.
+
+//solution
+// we want to do it in O(n) instead of O(n3) or O(nlgn)
+//so we need to follow greedy approach
+//we are storing 3 highest as well as 2 lowest values to get highest multiplication result
+//as 2 negative values can also be positive after multiplication
+#include<iostream>
+#include<bits/stdc++.h>
+#define pb push_back
+#define INF 1e9
+#define ll long long
+using namespace std;
+
+void solve()
+{
+	int n,temp;   //n = no. of values in list, temp is used for input
+	cin>>n;
+	vector<int> ar;   //ar is for storing problem list,
+	for(int i = 0; i<n; i++) 
+	{
+		cin>>temp;
+		ar.pb(temp);     //input
+	}
+	int low1= INF;
+	ll  low2=INF, high1=-INF, high2=-INF, high3=-INF, ans=1;   //storing maximum as well as lowest
+	for(int i=0; i<n; i++) //loop is for finding highest and lowest
+	{
+		if(high1<ar[i])
+		{
+			high3 = high2;
+			high2 = high1;
+			high1 = ar[i];
+			
+		}
+		else if(high2<ar[i])
+		{
+			high3 = high2;
+			high2 = ar[i];
+		}
+		else if(high3<ar[i])
+		{
+			high3 = ar[i];
+		}
+		
+		if(low1>ar[i])
+		{
+			low2 = low1;
+			low1 = ar[i];
+		}
+		else if(low2>ar[i]){
+			low2 = ar[i];
+		}
+	}
+	ans = high3* (low1*low2<high1*high2?high1*high2:low1*low2); //getting answer
+	cout<< ans<<"\n";
+}
+
+int main()
+{
+	int t;  //test cases
+	cin>>t;
+	while(t--)
+	{
+		solve(); //calling solve method to print output
+	}
+	return 0;
+}
diff --git a/Greedy Algorithms/merging meetings/cpp/meetings.cpp b/Greedy Algorithms/merging meetings/cpp/meetings.cpp
new file mode 100644
index 000000000..9d7b10a61
--- /dev/null
+++ b/Greedy Algorithms/merging meetings/cpp/meetings.cpp	
@@ -0,0 +1,117 @@
+//problem
+//Your company built an in-house calendar tool called HiCal. You want to add a feature to see the times in a day when everyone is available.
+//To do this, you’ll need to know when any team is having a meeting. In HiCal, a meeting is stored as an instance of a Meeting class with integer member variables startTime and endTime. These integers represent the number of 30-minute blocks past 9:00am.
+
+//solution
+//as we need to get common free time of all employes, we need to merge given meeting timesand find-
+//free slots between them
+//step1: get sorted your list w.r.t. starting time.
+//step2: compare their ending times.
+//step3: merge meetings in place and get final list. 
+#include<iostream>
+#include<bits/stdc++.h>
+#define pb push_back
+#define INF 1e9
+#define ll long long
+using namespace std;
+
+class Meeting         					//meeting obects will be elements of list
+{
+private:
+    // number of 30 min blocks past 9:00 am
+    unsigned int startTime_;
+    unsigned int endTime_;
+
+public:
+    Meeting() :
+        startTime_(0),
+        endTime_(0)
+    {
+    }
+
+    Meeting(unsigned int startTime, unsigned int endTime) :
+        startTime_(startTime),
+        endTime_(endTime)
+    {
+    }
+
+    unsigned int getStartTime() const
+    {
+        return startTime_;
+    }
+
+    void setStartTime(unsigned int startTime)
+    {
+        startTime_ = startTime;
+    }
+
+    unsigned int getEndTime() const
+    {
+        return endTime_;
+    }
+
+    void setEndTime(unsigned int endTime)
+    {
+        endTime_ = endTime;
+    }
+
+    bool operator==(const Meeting& other) const
+    {
+        return
+            startTime_ == other.startTime_
+            && endTime_ == other.endTime_;
+    }
+};
+
+bool comp_by_start(Meeting &meeting1, Meeting &meeting2)  		// used for sorting with starting time
+{
+	return meeting1.getStartTime()<meeting2.getStartTime();
+}
+void merge_meetings(vector<Meeting> &v)
+{
+	sort(v.begin(), v.end(), comp_by_start); // sorted meetings w.r.t. starting time
+	for(int i=0; i<v.size()-1; i++)
+	{
+		if(v[i].getEndTime()<v[i+1].getStartTime())
+		{
+			continue;
+		}
+		else if(v[i].getEndTime()>=v[i+1].getEndTime())
+		{
+			v.erase(v.begin()+1+i);
+			i--;
+		}
+		else{
+			v[i].setEndTime(v[i+1].getEndTime());
+			v.erase(v.begin()+1+i);
+			i--;
+		}
+	}
+}
+
+int main()
+{
+	int t;  //test cases
+	cin>>t;
+	while(t--)
+	{
+		unsigned int n, temp1, temp2;
+		cout<<"enter no. of meetings";
+		cin>>n;
+		vector<Meeting> v(n);
+		for(int i=0; i<n; i++)
+		{
+			cout<<"enter meeting start and end times\n";
+			cin>>temp1;
+			cin>>temp2;
+			Meeting meet(temp1,temp2);
+			v.pb(meet);
+		}
+		merge_meetings(v);
+		cout<<"starttime	emdtime\n";
+		for(int i=0; i<v.size(); i++){
+			cout<<v[i].getStartTime()<<"		"<<v[i].getEndTime()<<endl;
+		}
+	}
+	return 0;
+}