Merge pull request #552 from kvedala/fixes/lgtm

[bugs/lgtm] code + doc fixes + lgtm corrections

CMakeLists.txt

@@ -47,7 +47,7 @@ set(CMAKE_C_STANDARD_REQUIRED YES)
 
 if(MSVC)
     add_compile_definitions(_CRT_SECURE_NO_WARNINGS)
-    add_compile_options(/Za)
+    # add_compile_options(/Za)
 endif(MSVC)
 
 find_library(MATH_LIBRARY m)

misc/cantor_set.c

@@ -1,54 +1,61 @@
+/**
+ * @file
+ * @brief Program to generate [Cantor ternary
+ * set](https://en.wikipedia.org/wiki/Cantor_set)
+ */
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-struct contour
+/** structure to define Cantor set */
+typedef struct _cantor_set
 {
-    double start;
-    double end;
-    struct contour *next;
-};
-typedef struct contour Contour;
-Contour *head;
+    double start;             /**< start of interval */
+    double end;               /**< end of interval */
+    struct _cantor_set *next; /**< pointer to next set */
+} CantorSet;
 
-void startList(double start_num, double end_num)
+/** Iterative constructor of all sets in the current level. This function
+ * dynamically allocates memory when creating new sets. These are freed by the
+ * function ::free_memory.
+ * @param head pointer to interval set instance to update
+ */
+void propagate(CantorSet *head)
 {
+    // if input is NULL, ignore the process
     if (head == NULL)
-    {
-        head = (Contour *)malloc(sizeof(Contour));
-        head->start = start_num;
-        head->end = end_num;
-        head->next = NULL;
-    }
-}
-
-void propagate(Contour *head)
-{
-    Contour *temp = head;
-
-    if (temp != NULL)
-    {
-        Contour *newNode = (Contour *)malloc(sizeof(Contour));
-        double diff = (((temp->end) - (temp->start)) / 3);
-
-        newNode->end = temp->end;
-        temp->end = ((temp->start) + diff);
-        newNode->start = (newNode->end) - diff;
-
-        newNode->next = temp->next;
-
-        temp->next = newNode;
-
-        propagate(temp->next->next);
-    }
-    else
         return;
+
+    CantorSet *temp = head;  // local pointer to track propagation
+
+    // create new node for the new set
+    CantorSet *newNode = (CantorSet *)malloc(sizeof(CantorSet));
+
+    // get 1/3rd of interval
+    double diff = (((temp->end) - (temp->start)) / 3);
+
+    // update interval ranges
+    newNode->end = temp->end;
+    temp->end = ((temp->start) + diff);
+    newNode->start = (newNode->end) - diff;
+
+    // update pointer to next set in this level
+    newNode->next = temp->next;
+
+    // point to next set
+    temp->next = newNode;
+
+    // create next set
+    propagate(temp->next->next);
 }
 
-void print(Contour *head)
+/** Print sets in the current range to `stdout`
+ * @param head pointer to first set in the current level
+ */
+void print(CantorSet *head)
 {
-    Contour *temp = head;
-    while (temp != NULL)
+    CantorSet *temp = head;
+    while (temp != NULL)  // print while a valid set is found
     {
         printf("\t");
         printf("[%lf] -- ", temp->start);
@@ -59,10 +66,23 @@ void print(Contour *head)
     printf("\n");
 }
 
+/** Clear memory allocated by ::propagate function.
+ * @param head pointer to first allocated instance.
+ */
+void free_memory(CantorSet *head)
+{
+    if (!head)
+        return;
+
+    if (head->next)
+        free_memory(head->next);
+
+    free(head);
+}
+
+/** Main function */
 int main(int argc, char const *argv[])
 {
-    head = NULL;
-
     int start_num, end_num, levels;
 
     if (argc < 2)
@@ -77,17 +97,27 @@ int main(int argc, char const *argv[])
         levels = atoi(argv[3]);
     }
 
-    startList(start_num, end_num);
+    if (start_num < 0 || end_num < 0 || levels < 0)
+    {
+        fprintf(stderr, "All numbers must be positive\n");
+        return -1;
+    }
 
+    CantorSet head = {.start = start_num, .end = end_num, .next = NULL};
+
+    // loop to propagate each level from top to bottom
     for (int i = 0; i < levels; i++)
     {
         printf("Level %d\t", i);
-        print(head);
-        propagate(head);
+        print(&head);
+        propagate(&head);
         printf("\n");
     }
     printf("Level %d\t", levels);
-    print(head);
+    print(&head);
+
+    // delete all memory allocated
+    free_memory(head.next);
 
     return 0;
 }

project_euler/problem_1/sol1.c

@@ -1,7 +1,7 @@
 /**
  * \file
  * \brief [Problem 1](https://projecteuler.net/problem=1) solution
- *
+ * \details
  * An Efficient code to print all the sum of all numbers that are multiples of 3
  * & 5 below N.
  */

project_euler/problem_401/sol1.c

@@ -129,7 +129,7 @@ int main(int argc, char **argv)
 
     if (argc == 2)
         N = strtoll(argv[1], NULL, 10);
-    else if (N > 2)
+    else if (argc > 2)
     {
         fprintf(stderr, "Wrong number of input arguments!\n");
         printf("Usage:\t ./sol1.c [N=1000]");

searching/binary_search.c

@@ -1,9 +1,24 @@
+/**
+ * @file
+ * @brief Program to perform [binary
+ * search](https://en.wikipedia.org/wiki/Binary_search_algorithm) of a target
+ * value in a given *sorted* array.
+ * @authors [James McDermott](https://github.com/theycallmemac) - recursive
+ * algorithm
+ * @authors [Krishna Vedala](https://github.com/kvedala) - iterative algorithm
+ */
+#include <assert.h>
 #include <stdio.h>
 
-// Recursive Function- It returns location of x assumiung array arr[l..r] is
-// present, otherwise -1
-
-int binarysearch(int arr[], int l, int r, int x)
+/** Recursive implementation
+ * \param[in] arr array to search
+ * \param l left index of search range
+ * \param r right index of search range
+ * \param x target value to search for
+ * \returns location of x assuming array arr[l..r] is present
+ * \returns -1 otherwise
+ */
+int binarysearch1(const int *arr, int l, int r, int x)
 {
     if (r >= l)
     {
@@ -15,28 +30,80 @@ int binarysearch(int arr[], int l, int r, int x)
 
         // If element is smaller than middle
         if (arr[mid] > x)
-            return binarysearch(arr, l, mid - 1, x);
+            return binarysearch1(arr, l, mid - 1, x);
 
         // Else element is in right subarray
-        return binarysearch(arr, mid + 1, r, x);
+        return binarysearch1(arr, mid + 1, r, x);
     }
 
     // When element is not present in array
     return -1;
 }
 
-int main(void)
+/** Iterative implementation
+ * \param[in] arr array to search
+ * \param l left index of search range
+ * \param r right index of search range
+ * \param x target value to search for
+ * \returns location of x assuming array arr[l..r] is present
+ * \returns -1 otherwise
+ */
+int binarysearch2(const int *arr, int l, int r, int x)
+{
+    int mid = l + (r - l) / 2;
+
+    while (arr[mid] != x)
+    {
+        if (r <= l || r < 0)
+            return -1;
+
+        if (arr[mid] > x)
+            // If element is smaller than middle
+            r = mid - 1;
+        else
+            // Else element is in right subarray
+            l = mid + 1;
+
+        mid = l + (r - l) / 2;
+    }
+
+    // When element is not present in array
+    return mid;
+}
+
+/** Test implementations */
+void test()
 {
     // give function an array to work with
     int arr[] = {2, 3, 4, 10, 40};
     // get size of array
     int n = sizeof(arr) / sizeof(arr[0]);
+
+    printf("Test 1.... ");
     // set value to look for
     int x = 10;
     // set result to what is returned from binarysearch
-    int result = binarysearch(arr, 0, n - 1, x);
-    // print out result
-    (result == -1) ? printf("Element is not in the array\n")
-                   : printf("Element is present at index %d\n", result);
+    int result = binarysearch1(arr, 0, n - 1, x);
+    assert(result == 3);
+    printf("passed recursive... ");
+    result = binarysearch2(arr, 0, n - 1, x);
+    assert(result == 3);
+    printf("passed iterative...\n");
+
+    printf("Test 2.... ");
+    x = 5;
+    // set result to what is returned from binarysearch
+    result = binarysearch1(arr, 0, n - 1, x);
+    assert(result == -1);
+    printf("passed recursive... ");
+    result = binarysearch2(arr, 0, n - 1, x);
+    assert(result == -1);
+    printf("passed iterative...\n");
+}
+
+/** Main function */
+int main(void)
+{
+    test();
     return 0;
 }