arrays

Author: Parth Garg

05. Arrays/01 Linear Search/01 Linear Search.cpp

@@ -0,0 +1,27 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n) for unsorted array
+//Time: O(logn) for sorted array (Binary Search)
+int linearSearch(int arr[], int n, int key)
+{
+    for (int i = 0; i < n; i++)
+    {
+        if (arr[i] == key)
+        {
+            return i;
+        }
+    }
+
+    return -1;
+}
+
+int main()
+{
+    int arr[] = {3, 2, 4, 1, 5};
+    int n = sizeof(arr) / sizeof(int);
+    int key = 1;
+
+    cout << linearSearch(arr, n, key) << endl;
+    return 0;
+}

05. Arrays/02 Insert/02 Insert.cpp

@@ -0,0 +1,41 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n) insert at begin
+//Time: O(1) insert at end
+int insert(int arr[], int n, int key, int pos)
+{
+    for (int i = n - 1; i >= pos - 1; i--)
+    {
+        arr[i + 1] = arr[i];
+    }
+    arr[pos - 1] = key;
+    n++;
+
+    return n;
+}
+
+void display(int arr[], int n)
+{
+    for (int i = 0; i < n; i++)
+    {
+        cout << arr[i] << " ";
+    }
+    cout << endl;
+
+    return ;
+}
+
+int main()
+{
+    int arr[] = {3, 2, 4, 1, 5};
+    int n = sizeof(arr) / sizeof(int);
+    int key = 6;
+    int pos = 3;
+
+    display(arr, n);
+    n = insert(arr, n, key, pos);
+    display(arr, n);
+
+    return 0;
+}

05. Arrays/03 Delete/03 Delete.cpp

@@ -0,0 +1,53 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n) delete at begin
+//Time: O(1) delete at end
+int del(int arr[], int n, int key)
+{
+    int idx, i;
+    for (i = 0; i < n; i++)
+    {
+        if (key == arr[i])
+        {
+            idx = i;
+            break;
+        }
+    }
+
+    if (i == n)
+    {
+        return n;
+    }
+
+    for (int i = idx; i < n - 1; i++)
+    {
+        arr[i] = arr[i + 1];
+    }
+    n--;
+
+    return n;
+}
+
+void display(int arr[], int n)
+{
+    for (int i = 0; i < n; i++)
+    {
+        cout << arr[i] << " ";
+    }
+    cout << endl;
+
+    return ;
+}
+
+int main()
+{
+    int arr[] = {3, 2, 4, 1, 5};
+    int n = sizeof(arr) / sizeof(int);
+    int key = 4;
+
+    display(arr, n);
+    n = del(arr, n, key);
+    display(arr, n);
+    return 0;
+}

05. Arrays/04 Largest Element/04 Largest Element.cpp

@@ -0,0 +1,26 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n)
+int largest(int a[], int n)
+{
+    int max_element = INT_MIN;
+    for (int i = 0; i < n; i++)
+    {
+        if (a[i] > max_element)
+        {
+            max_element = a[i];
+        }
+    }
+
+    return max_element;
+}
+
+int main()
+{
+    int arr[] = {3, 2, 4, 5, 1};
+    int n = sizeof(arr) / sizeof(int);
+
+    cout << largest(arr, n) << endl;
+    return 0;
+}

05. Arrays/05 Second Largest Element/05a Second Largest Element.cpp

@@ -0,0 +1,47 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int largest(int a[], int n)
+{
+    int max = INT_MIN;
+    for (int i = 0; i < n; i++)
+    {
+        if (a[i] > max)
+        {
+            max = a[i];
+        }
+    }
+
+    return max;
+}
+
+//Time: O(n) (two traversals)
+int secondLargest(int arr[], int n)
+{
+    int max = largest(arr, n);
+    int res = INT_MIN;
+    int i;
+    for (i = 0; i < n; i++)
+    {
+        if (res < arr[i] and arr[i] != max)
+        {
+            res = arr[i];
+        }
+    }
+
+    if(res==INT_MIN)
+    {
+        return -1;
+    }
+
+    return res;
+}
+
+int main()
+{
+    int arr[] = {3, 2, 4, 1, 5};
+    int n = sizeof(arr) / sizeof(int);
+
+    cout << secondLargest(arr, n) << endl;
+    return 0;
+}

05. Arrays/05 Second Largest Element/05b Second Largest Element.cpp

@@ -0,0 +1,33 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n) (one traversal)
+int secondLargest(int arr[], int n)
+{
+    int greatest, secondGreatest;
+    greatest = secondGreatest = -1;
+
+    for (int i = 0; i < n; i++)
+    {
+        if (arr[i] > greatest)
+        {
+            secondGreatest = greatest;
+            greatest = arr[i];
+        }
+        if (arr[i]<greatest and arr[i]>secondGreatest)
+        {
+            secondGreatest = arr[i];
+        }
+    }
+
+    return secondGreatest;
+}
+
+int main()
+{
+    int arr[] = {3, 2, 4, 1, 5};
+    int n = sizeof(arr) / sizeof(int);
+
+    cout << secondLargest(arr, n) << endl;
+    return 0;
+}

05. Arrays/06 Check Array Sorted/06 Check Array Sorted.cpp

@@ -0,0 +1,30 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n)
+bool sorted(int a[], int n)
+{
+    if (n <= 1)
+    {
+        return true;
+    }
+
+    for (int i = 0; i < n - 1; i++)
+    {
+        if (a[i] > a[i + 1])
+        {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+int main()
+{
+    int arr[] = {3, 4, 5, 1, 2};
+    int n = sizeof(arr) / sizeof(int);
+
+    cout << sorted(arr, n) << endl;
+    return 0;
+}

05. Arrays/07 Reverse Array/07 Reverse Array.cpp

@@ -0,0 +1,40 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n)
+void reverse(int a[], int n)
+{
+    if (n <= 1)
+    {
+        return ;
+    }
+
+    int i = 0;
+    int j = n - 1;
+    while (i < j)
+    {
+        swap(a[i], a[j]);
+        i++;
+        j--;
+    }
+}
+
+void display(int a[], int n)
+{
+    for (int i = 0; i < n; i++)
+    {
+        cout << a[i] << " ";
+    }
+    cout << endl;
+}
+
+int main()
+{
+    int arr[] = {3, 2, 4, 1, 5};
+    int n = sizeof(arr) / sizeof(int);
+
+    display(arr, n);
+    reverse(arr, n);
+    display(arr, n);
+    return 0;
+}

05. Arrays/08 Remove Duplicates from Sorted Array/08 Remove Duplicates from Sorted Array.cpp

@@ -0,0 +1,39 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n)
+int removeDuplicate(int a[], int n)
+{
+    int res=1;
+    for(int i=1;i<n;i++)
+    {
+        if(a[i]!=a[res-1])
+        {
+            a[res]=a[i];
+            res++;
+        }
+    }
+
+    return res;
+}
+
+void display(int a[], int n)
+{
+    for (int i = 0; i < n; i++)
+    {
+        cout << a[i] << " ";
+    }
+    cout << endl;
+}
+
+int main()
+{
+    int arr[] = {10,20,20,30,30,30};
+    int n = sizeof(arr) / sizeof(int);
+
+    display(arr, n);
+    n = removeDuplicate(arr, n);
+    display(arr, n);
+
+    return 0;
+}

05. Arrays/09 Move Zeros to End/09a Move Zero to End.cpp

@@ -0,0 +1,42 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+//Time: O(n^2)
+void moveZeros(int a[], int n)
+{
+    for (int i = 0; i < n; i++)
+    {
+        if (a[i] == 0)
+        {
+            for (int j = i + 1; j < n; j++)
+            {
+                if (a[j] != 0)
+                {
+                    swap(a[i], a[j]);
+                    break;
+                }
+            }
+        }
+    }
+}
+
+void display(int a[], int n)
+{
+    for (int i = 0; i < n; i++)
+    {
+        cout << a[i] << " ";
+    }
+    cout << endl;
+}
+
+int main()
+{
+    int arr[] = {0, 3, 2, 1, 0, 4, 7, 0, 2};
+    int n = sizeof(arr) / sizeof(int);
+
+    display(arr, n);
+    moveZeros(arr, n);
+    display(arr, n);
+
+    return 0;
+}