Oops, copied the wrong file...

Author: pascalecu

archive/c/c/depth-first-search.c

@@ -1,197 +1,96 @@
-#include <ctype.h>
+#include <math.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-typedef struct
-{
-    int x;
-    int y;
-} Point;
+#define MAX_NODES 100
 
-void printUsageAndExit()
-{
-    printf("Usage: please provide at least 3 x and y coordinates as separate "
-           "lists (e.g. \"100, 440, 210\")\n");
-    exit(1);
-}
+int adjacency_matrix[MAX_NODES][MAX_NODES];
+int vertex_values[MAX_NODES];
+int num_nodes;
+bool visited[MAX_NODES];
 
-int compare(const void *p1, const void *p2)
+bool dfs(int node, int target)
 {
-    Point *point1 = (Point *)p1;
-    Point *point2 = (Point *)p2;
-
-    if (point1->x != point2->x)
-        return point1->x - point2->x;
-    return point1->y - point2->y;
-}
-
-int orientation(Point p, Point q, Point r)
-{
-    int val = (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
-    return (val == 0) ? 0 : (val > 0) ? 1 : 2;
-}
-
-void convexHull(Point points[], int n)
-{
-    Point hull[n];
-    int hullCount = 0;
-
-    qsort(points, n, sizeof(Point), compare);
-
-    int l = 0;
-    for (int i = 1; i < n; i++)
-        if (points[i].x < points[l].x)
-            l = i;
-
-    int p = l, q;
-    do
+    if (vertex_values[node] == target)
+        return true;
+    visited[node] = true;
+    for (int i = 0; i < num_nodes; i++)
     {
-        hull[hullCount++] = points[p];
-        q = (p + 1) % n;
-
-        for (int i = 0; i < n; i++)
-            if (orientation(points[p], points[i], points[q]) == 2)
-                q = i;
-
-        p = q;
-    } while (p != l);
-
-    for (int i = 0; i < hullCount; i++)
-        printf("(%d, %d)\n", hull[i].x, hull[i].y);
-}
-
-// Function to check if a string is a valid number
-bool isInteger(const char *s)
-{
-    char *end;
-    strtol(s, &end, 10); // Convert string to long
-    return (*end == '\0'
-            || *end == '\n'); // Check if the entire string was valid
+        if (adjacency_matrix[node][i] && !visited[i])
+        {
+            if (dfs(i, target))
+                return true;
+        }
+    }
+    return false;
 }
 
-// Function to trim whitespace from a string
-char *trimWhitespace(char *str)
+bool depth_first_search(int target)
 {
-    // Trim leading whitespace
-    while (isspace((unsigned char)*str))
-        str++;
-    // Trim trailing whitespace
-    char *end = str + strlen(str) - 1;
-    while (end > str && isspace((unsigned char)*end))
-        end--;
-    *(end + 1) = '\0'; // Null terminate after the last non-space character
-    return str;
+    memset(visited, 0, sizeof(visited));
+    for (int i = 0; i < num_nodes; i++)
+        if (!visited[i] && dfs(i, target))
+            return true;
+    return false;
 }
 
-// Function to parse input string and populate the array
-int parseInput(const char *input, int **arr, int *size)
+void parse_matrix(char *input)
 {
-    char *token;
-    int capacity = 10; // Initial capacity
-    *arr = malloc(capacity * sizeof(int));
-    if (*arr == NULL)
-        return false;
-
-    // Tokenize the input string based on commas
-    char *inputCopy = strdup(input);
-    if (inputCopy == NULL)
-    {
-        free(*arr);
-        *arr = NULL;
-        return false;
-    }
-
-    token = strtok(inputCopy, ",");
-    *size = 0;
-    while (token)
+    char *token = strtok(input, ", ");
+    int i = 0, j = 0;
+    while (token != NULL)
     {
-        trimWhitespace(token); // Trim whitespace around token
-        if (!isInteger(token))
+        adjacency_matrix[i][j] = atoi(token);
+        j++;
+        if (j == num_nodes)
         {
-            free(*arr);
-            free(inputCopy);
-            *arr = NULL;
-            return false; // Exit if a number is invalid
+            i++;
+            j = 0;
         }
-
-        if (*size >= capacity)
-        {
-            capacity *= 2;
-            *arr = realloc(*arr, capacity * sizeof(int));
-            if (*arr == NULL)
-            {
-                free(inputCopy);
-                return false;
-            }
-        }
-        (*arr)[(*size)++] = atoi(token);
-        token = strtok(NULL, ",");
+        token = strtok(NULL, ", ");
     }
-
-    // Resize the array to the actual size
-    *arr = realloc(*arr, *size * sizeof(int));
-    free(inputCopy); // Free the input copy
-    if (*arr == NULL)
-        return false;
-
-    return true; // Successful parsing
 }
 
-void parseCoordinates(char *inputX, char *inputY)
+void parse_values(char *input)
 {
-    int *xCoords = NULL;
-    int *yCoords = NULL;
-    int xSize = 0;
-    int ySize = 0;
-    if (!parseInput(inputX, &xCoords, &xSize)
-        || !parseInput(inputY, &yCoords, &ySize)
-        || xSize != ySize
-        || xSize < 3)
+    char *token = strtok(input, ", ");
+    int i = 0;
+    while (token != NULL)
     {
-        if (xCoords != NULL)
-            free(xCoords);
-
-        if (yCoords != NULL)
-            free(yCoords);
-
-        printUsageAndExit();
-    }
-
-    int count = xSize;
-    Point *points = malloc(sizeof(Point) * count);
-    if (points == NULL)
-    {
-        free(xCoords);
-        free(yCoords);
-        printUsageAndExit();
+        vertex_values[i++] = atoi(token);
+        token = strtok(NULL, ", ");
     }
+}
 
-    for (int i = 0; i < count; i++)
+int main(int argc, char *argv[])
+{
+    if (argc != 4 || !*argv[1] || !*argv[2] || !*argv[3])
     {
-        points[i].x = xCoords[i];
-        points[i].y = yCoords[i];
+        printf("Usage: please provide a tree in an adjacency matrix form (\"0, "
+               "1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, "
+               "1, 0, 0\") together with a list of vertex values (\"1, 3, 5, "
+               "2, 4\") and the integer to find (\"4\")");
+        return 1;
     }
 
-    free(xCoords);
-    free(yCoords);
+    char *matrix_str = argv[1];
+    char *values_str = argv[2];
+    int target = atoi(argv[3]);
 
-    convexHull(points, count);
-    free(points);
-}
+    int total_elements = 1;
+    for (char *p = matrix_str; *p; p++)
+        if (*p == ',')
+            total_elements++;
 
-int main(int argc, char *argv[])
-{
-    if (argc != 3)
-        printUsageAndExit();
+    num_nodes = (int)sqrt(total_elements);
 
-    char *inputX = argv[1];
-    char *inputY = argv[2];
+    parse_matrix(matrix_str);
+    parse_values(values_str);
 
-    if (strlen(inputX) == 0 || strlen(inputY) == 0)
-        printUsageAndExit();
+    bool result = depth_first_search(target);
+    printf(result ? "true\n" : "false\n");
 
-    parseCoordinates(inputX, inputY);
     return 0;
 }