Add Dijkstra in C (#4322)

Author: 2Clutch

archive/c/c/dijkstra.c

@@ -0,0 +1,92 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <math.h>
+
+#define MAX_NODES 100
+
+int dijkstra(int graph[MAX_NODES][MAX_NODES], int src, int dest, int n) {
+    int dist[MAX_NODES];
+    bool sptSet[MAX_NODES];
+
+    for (int i = 0; i < n; i++) {
+        dist[i] = INT_MAX;
+        sptSet[i] = false;
+    }
+
+    dist[src] = 0;
+
+    for (int count = 0; count < n - 1; count++) {
+        int min = INT_MAX, min_index;
+
+        for (int v = 0; v < n; v++)
+            if (sptSet[v] == false && dist[v] <= min)
+                min = dist[v], min_index = v;
+
+        int u = min_index;
+        sptSet[u] = true;
+
+        for (int v = 0; v < n; v++)
+            if (!sptSet[v] && graph[u][v] && dist[u] != INT_MAX
+                && dist[u] + graph[u][v] < dist[v])
+                dist[v] = dist[u] + graph[u][v];
+    }
+
+    return dist[dest] == INT_MAX ? -1 : dist[dest];
+}
+
+int main(int argc, char *argv[]) {
+    if (argc != 4) {
+        printf("Usage: please provide three inputs: a serialized matrix, a source node and a destination node\n");
+        return 1;
+    }
+
+    char *matrix = argv[1];
+    char *src_str = argv[2];
+    char *dest_str = argv[3];
+
+    // Check for empty inputs
+    if (strlen(matrix) == 0 || strlen(src_str) == 0 || strlen(dest_str) == 0) {
+        printf("Usage: please provide three inputs: a serialized matrix, a source node and a destination node\n");
+        return 1;
+    }
+
+    int src = atoi(src_str);
+    int dest = atoi(dest_str);
+
+    long long n = 0;
+    for (size_t i = 0; matrix[i]; i++) {
+        if (matrix[i] == ',') n++;
+    }
+    n = (long long)sqrt((double)n + 1);
+
+    if (src < 0 || dest < 0 || src >= n || dest >= n) {
+        printf("Usage: please provide three inputs: a serialized matrix, a source node and a destination node\n");
+        return 1;
+    }
+
+    int graph[MAX_NODES][MAX_NODES] = {0};
+    char *token = strtok(matrix, ", ");
+    for (int i = 0; i < n && token; i++) {
+        for (int j = 0; j < n && token; j++) {
+            int weight = atoi(token);
+            if (weight < 0) {
+                printf("Usage: please provide three inputs: a serialized matrix, a source node and a destination node\n");
+                return 1;
+            }
+            graph[i][j] = weight;
+            token = strtok(NULL, ", ");
+        }
+    }
+
+    int result = dijkstra(graph, src, dest, (int)n);
+    if (result == -1) {
+        printf("Usage: please provide three inputs: a serialized matrix, a source node and a destination node\n");
+    } else {
+        printf("%d\n", result);
+    }
+
+    return 0;
+}