files renamed to standard - without spaces and made CPPLINT compatible

others/GCD_of_n_numbers.cpp

@@ -1,23 +1,22 @@
-//This program aims at calculating the GCD of n numbers by division method
+// This program aims at calculating the GCD of n numbers by division method
 #include <iostream>
-using namepsace std;
-int main()
-{
-  cout << "Enter value of n:" << endl;
-  cin >> n;
-  int a[n];
-  int i, j, gcd;
-  cout << "Enter the n numbers:" << endl;
-  for (i = 0; i < n; i++)
-    cin >> a[i];
-  j = 1; //to access all elements of the array starting from 1
-  gcd = a[0];
-  while (j < n)
-  {
-    if (a[j] % gcd == 0) //value of gcd is as needed so far
-      j++;               //so we check for next element
-    else
-      gcd = a[j] % gcd; //calculating GCD by division method
-  }
-  cout << "GCD of entered n numbers:" << gcd;
+
+int main() {
+    int n;
+    std::cout << "Enter value of n:" << std::endl;
+    std::cin >> n;
+    int a[n];
+    int i, j, gcd;
+    std::cout << "Enter the n numbers:" << std::endl;
+    for (i = 0; i < n; i++) std::cin >> a[i];
+    j = 1;  // to access all elements of the array starting from 1
+    gcd = a[0];
+    while (j < n) {
+        if (a[j] % gcd == 0)  // value of gcd is as needed so far
+            j++;              // so we check for next element
+        else
+            gcd = a[j] % gcd;  // calculating GCD by division method
+    }
+    std::cout << "GCD of entered n numbers:" << gcd;
+    return 0;
 }

others/fibonacci.cpp

@@ -1,42 +0,0 @@
-//An efficient way to calculate nth fibonacci number faster and simpler than O(nlogn) method of matrix exponentiation
-//This works by using both recursion and dynamic programming.
-//as 93rd fibonacci exceeds 19 digits, which cannot be stored in a single long long variable, we can only use it till 92nd fibonacci
-//we can use it for 10000th fibonacci etc, if we implement bigintegers.
-//This algorithm works with the fact that nth fibonacci can easily found if we have already found n/2th or (n+1)/2th fibonacci
-//It is a property of fibonacci similar to matrix exponentiation.
-
-#include <iostream>
-#include <cstdio>
-using namespace std;
-
-const long long MAX = 93;
-
-long long f[MAX] = {0};
-
-long long fib(long long n)
-{
-
-    if (n == 0)
-        return 0;
-    if (n == 1 || n == 2)
-        return (f[n] = 1);
-
-    if (f[n])
-        return f[n];
-
-    long long k = (n % 2 != 0) ? (n + 1) / 2 : n / 2;
-
-    f[n] = (n % 2 != 0) ? (fib(k) * fib(k) + fib(k - 1) * fib(k - 1))
-                        : (2 * fib(k - 1) + fib(k)) * fib(k);
-    return f[n];
-}
-
-int main()
-{
-    //Main Function
-    for (long long i = 1; i < 93; i++)
-    {
-        cout << i << " th fibonacci number is " << fib(i) << "\n";
-    }
-    return 0;
-}

others/fibonacci_fast.cpp

@@ -0,0 +1,37 @@
+// An efficient way to calculate nth fibonacci number faster and simpler than
+// O(nlogn) method of matrix exponentiation This works by using both recursion
+// and dynamic programming. as 93rd fibonacci exceeds 19 digits, which cannot be
+// stored in a single long long variable, we can only use it till 92nd fibonacci
+// we can use it for 10000th fibonacci etc, if we implement bigintegers.
+// This algorithm works with the fact that nth fibonacci can easily found if we
+// have already found n/2th or (n+1)/2th fibonacci It is a property of fibonacci
+// similar to matrix exponentiation.
+
+#include <cstdio>
+#include <iostream>
+using namespace std;
+
+const long long MAX = 93;
+
+long long f[MAX] = {0};
+
+long long fib(long long n) {
+    if (n == 0) return 0;
+    if (n == 1 || n == 2) return (f[n] = 1);
+
+    if (f[n]) return f[n];
+
+    long long k = (n % 2 != 0) ? (n + 1) / 2 : n / 2;
+
+    f[n] = (n % 2 != 0) ? (fib(k) * fib(k) + fib(k - 1) * fib(k - 1))
+                        : (2 * fib(k - 1) + fib(k)) * fib(k);
+    return f[n];
+}
+
+int main() {
+    // Main Function
+    for (long long i = 1; i < 93; i++) {
+        cout << i << " th fibonacci number is " << fib(i) << "\n";
+    }
+    return 0;
+}

others/matrix_exponentiation.cpp

@@ -19,6 +19,8 @@ The first element of this matrix is the required result.
 */
 
 #include <iostream>
+#include <vector>
+
 using std::cin;
 using std::cout;
 using std::vector;
@@ -46,8 +48,7 @@ vector<vector<ll>> multiply(vector<vector<ll>> A, vector<vector<ll>> B) {
 
 // computing power of a matrix
 vector<vector<ll>> power(vector<vector<ll>> A, ll p) {
-    if (p == 1)
-        return A;
+    if (p == 1) return A;
     if (p % 2 == 1) {
         return multiply(A, power(A, p - 1));
     } else {
@@ -58,14 +59,11 @@ vector<vector<ll>> power(vector<vector<ll>> A, ll p) {
 
 // main function
 ll ans(ll n) {
-    if (n == 0)
-        return 0;
-    if (n <= k)
-        return b[n - 1];
+    if (n == 0) return 0;
+    if (n <= k) return b[n - 1];
     // F1
     vector<ll> F1(k + 1);
-    for (ll i = 1; i <= k; i++)
-        F1[i] = b[i - 1];
+    for (ll i = 1; i <= k; i++) F1[i] = b[i - 1];
 
     // Transpose matrix
     vector<vector<ll>> T(k + 1, vector<ll>(k + 1));

others/pascal_triangle.cpp

@@ -1,63 +1,53 @@
-#include<iostream>
+#include <cstring>
+#include <iostream>
 
-using namespace std;
-
-void show_pascal(int **arr, int n)
-{
-	//pint Pascal's Triangle
-	for (int i = 0; i < n; ++i)
-	{
-		for (int j = 0; j < n + i; ++j)
-		{
-			if (arr[i][j] == 0)
-				cout << " ";
-			else
-				cout << arr[i][j];
-		}
-		cout << endl;
-	}
+void show_pascal(int **arr, int n) {
+    // pint Pascal's Triangle
+    for (int i = 0; i < n; ++i) {
+        for (int j = 0; j < n + i; ++j) {
+            if (arr[i][j] == 0)
+                std::cout << " ";
+            else
+                std::cout << arr[i][j];
+        }
+        std::cout << std::endl;
+    }
 }
 
-int **pascal_triangle(int **arr, int n)
-{
-	for (int i = 0; i < n; ++i)
-	{
-		for (int j = n - i - 1; j < n + i; ++j)
-		{
-			if (j == n - i - 1 || j == n + i - 1)
-				arr[i][j] = 1;				//The edge of the Pascal triangle goes in 1
-			else
-				arr[i][j] = arr[i - 1][j - 1] + arr[i - 1][j + 1];
-		}
-	}
+int **pascal_triangle(int **arr, int n) {
+    for (int i = 0; i < n; ++i) {
+        for (int j = n - i - 1; j < n + i; ++j) {
+            if (j == n - i - 1 || j == n + i - 1)
+                arr[i][j] = 1;  // The edge of the Pascal triangle goes in 1
+            else
+                arr[i][j] = arr[i - 1][j - 1] + arr[i - 1][j + 1];
+        }
+    }
 
-	return arr;
+    return arr;
 }
 
-int main()
-{
-	int n = 0;
+int main() {
+    int n = 0;
 
-	cout << "Set Pascal's Triangle Height" << endl;
-	cin >> n;
-	
-	//memory allocation (Assign two-dimensional array to store Pascal triangle)
-	int **arr = new int*[n];
-	for (int i = 0; i < n; ++i)
-	{
-		arr[i] = new int[2 * n - 1];
-		memset(arr[i], 0, sizeof(int)*(2 * n - 1));
-	}
-	
-	pascal_triangle(arr, n);
-	show_pascal(arr, n);
+    std::cout << "Set Pascal's Triangle Height" << std::endl;
+    std::cin >> n;
 
-	//deallocation
-	for (int i = 0; i < n; ++i)
-	{
-		delete[] arr[i];
-	}
-	delete[] arr;
+    // memory allocation (Assign two-dimensional array to store Pascal triangle)
+    int **arr = new int *[n];
+    for (int i = 0; i < n; ++i) {
+        arr[i] = new int[2 * n - 1];
+        memset(arr[i], 0, sizeof(int) * (2 * n - 1));
+    }
 
-	return 0;
+    pascal_triangle(arr, n);
+    show_pascal(arr, n);
+
+    // deallocation
+    for (int i = 0; i < n; ++i) {
+        delete[] arr[i];
+    }
+    delete[] arr;
+
+    return 0;
 }

sorting/shell_sort2.cpp

@@ -0,0 +1,105 @@
+#include <array>
+#include <cstdlib>
+#include <ctime>
+#include <iostream>
+
+// for std::swap
+#include <utility>
+
+template <class T> void show_data(T *arr, size_t LEN) {
+  size_t i;
+
+  for (i = 0; i < LEN; i++)
+    std::cout << arr[i] << ", ";
+  std::cout << std::endl;
+}
+
+template <class T, size_t N> void show_data(T (&arr)[N]) { show_data(arr, N); }
+
+/**
+ * Optimized algorithm - takes half the time by utilizing
+ * Mar
+ **/
+template <class T> void shell_sort(T *arr, size_t LEN) {
+  const unsigned int gaps[] = {701, 301, 132, 57, 23, 10, 4, 1};
+  const unsigned int gap_len = 8;
+  size_t i, j, g;
+
+  for (g = 0; g < gap_len; g++) {
+    unsigned int gap = gaps[g];
+    for (i = gap; i < LEN; i++) {
+      T tmp = arr[i];
+
+      for (j = i; j >= gap && (arr[j - gap] - tmp) > 0; j -= gap)
+        arr[j] = arr[j - gap];
+
+      arr[j] = tmp;
+    }
+  }
+}
+
+template <class T, size_t N> void shell_sort(T (&arr)[N]) {
+  shell_sort(arr, N);
+}
+
+/**
+ * function to compare sorting using cstdlib's qsort
+ **/
+int compare(const void *a, const void *b) {
+  int arg1 = *static_cast<const int *>(a);
+  int arg2 = *static_cast<const int *>(b);
+
+  if (arg1 < arg2)
+    return -1;
+  if (arg1 > arg2)
+    return 1;
+  return 0;
+
+  //  return (arg1 > arg2) - (arg1 < arg2); // possible shortcut
+  //  return arg1 - arg2; // erroneous shortcut (fails if INT_MIN is present)
+}
+
+int main(int argc, char *argv[]) {
+  int i, NUM_DATA;
+
+  if (argc == 2)
+    NUM_DATA = atoi(argv[1]);
+  else
+    NUM_DATA = 200;
+
+  // int array = new int[NUM_DATA];
+  int *data = new int[NUM_DATA];
+  int *data2 = new int[NUM_DATA];
+  // int array2 = new int[NUM_DATA];
+  int range = 1800;
+
+  std::srand(time(NULL));
+  for (i = 0; i < NUM_DATA; i++)
+    data[i] = data2[i] = (std::rand() % range) - (range >> 1);
+
+  std::cout << "Unsorted original data: " << std::endl;
+  show_data(data, NUM_DATA);
+  std::clock_t start = std::clock();
+  shell_sort(data, NUM_DATA);
+  std::clock_t end = std::clock();
+
+  std::cout << std::endl
+            << "Data Sorted using custom implementation: " << std::endl;
+  show_data(data, NUM_DATA);
+
+  double elapsed_time = (end - start) * 1.f / CLOCKS_PER_SEC;
+  std::cout << "Time spent sorting: " << elapsed_time << "s\n" << std::endl;
+
+  start = std::clock();
+  qsort(data2, NUM_DATA, sizeof(data2[0]), compare);
+  end = std::clock();
+  std::cout << "Data Sorted using cstdlib qsort: " << std::endl;
+  show_data(data2, NUM_DATA);
+
+  elapsed_time = (end - start) * 1.f / CLOCKS_PER_SEC;
+  std::cout << "Time spent sorting: " << elapsed_time << "s\n" << std::endl;
+
+  free(data);
+  free(data2);
+  return 0;
+}