Graph Coloring

Backtracking/Graph Coloring.cpp

@@ -0,0 +1,81 @@
+#include<stdio.h>
+ 
+// Number of vertices in the graph
+#define V 4
+ 
+void printSolution(int color[]);
+ 
+/* A utility function to check if the current color assignment
+   is safe for vertex v */
+bool isSafe (int v, bool graph[V][V], int color[], int c)
+{
+    for (int i = 0; i < V; i++)
+        if (graph[v][i] && c == color[i])
+            return false;
+    return true;
+}
+ 
+/* A recursive utility function to solve m coloring problem */
+void graphColoring(bool graph[V][V], int m, int color[], int v)
+{
+    /* base case: If all vertices are assigned a color then
+       return true */
+    if (v == V){
+    	printSolution(color);
+        return;
+    }
+ 
+    /* Consider this vertex v and try different colors */
+    for (int c = 1; c <= m; c++)
+    {
+        /* Check if assignment of color c to v is fine*/
+        if (isSafe(v, graph, color, c))
+        {
+           color[v] = c;
+ 
+           /* recur to assign colors to rest of the vertices */
+           graphColoring (graph, m, color, v+1);
+            
+ 
+            /* If assigning color c doesn't lead to a solution
+               then remove it */
+           color[v] = 0;
+        }
+    }
+ 
+}
+
+/* A utility function to print solution */
+void printSolution(int color[])
+{
+    printf(" Following are the assigned colors \n");
+    for (int i = 0; i < V; i++)
+      printf(" %d ", color[i]);
+    printf("\n");
+}
+ 
+// driver program to test above function
+int main()
+{
+    /* Create following graph and test whether it is 3 colorable
+      (3)---(2)
+       |   / |
+       |  /  |
+       | /   |
+      (0)---(1)
+    */
+    bool graph[V][V] = {{0, 1, 1, 1},
+        {1, 0, 1, 0},
+        {1, 1, 0, 1},
+        {1, 0, 1, 0},
+    };
+    int m = 3; // Number of colors
+
+	int color[V];
+
+	for (int i = 0; i < V; i++)
+        color[i] = 0;
+    
+    graphColoring(graph, m, color, 0);
+    return 0;
+}