Added README.md

GraphBuilder/README.md

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+# Class GraphBuilder
+
+Creates graph in form of jagged arrays (as compared to Arraylist) for directed as well as undirected graphs from given set of edges in 0 indexing.
+
+All members of this class are static, so no constructor defined.
+
+## Methods
+
+### makeGraph
+```
+public static int[][] makeGraph(int NumberOfNodes, int NumberOfEdges, int[] from, int[] to, boolean undirected)
+```
+Returns the adjacency list representation of graph with specified Number of Nodes and Edges and the edges specified in from and to arrays in 0-based indexing. If undirected is set to true, the edges are deemed to be undirected, otherwise directed.
+
+```graph[u]``` is the array of vertices having an edge outgoing from vertex u.
+
+** Constraints **
+* 0 \leq from[i], to[i] < NumberOfNodes
+* from.length = to.length = NumberOfEdges
+
+** Computational complexity **
+* $ O (NumberOfNodes + NumberOfEdges) $
+
+### makeGraphWithEdgeInfo
+```
+public static int[][][] makeGraphWithEdgeInfo(int NumberOfNodes, int NumberOfEdges, int[] from, int[] to, boolean undirected)
+```
+
+Returns the adjacency list representation of graph with specified Number of Nodes and Edges and the edges specified in from and to arrays in 0-based indexing. If undirected is set to true, the edges are deemed to be undirected, otherwise directed. This method also returns useful information about edge index and edge direction.
+
+```graph[u]``` is the array of tuples ```[v, idx, direction]``` where edge indexed ```idx``` is between node ```u``` and node ```v``` and direction takes value either $0$ or $1$.
+- If direction is $0$, edge indexed ```idx``` is from ```u``` to ```v```
+- If direction is $1$, edge indexed ```idx``` is from ```v``` to ```u```
+
+** Constraints **
+* 0 \leq from[i], to[i] < NumberOfNodes
+* from.length = to.length = NumberOfEdges
+
+** Computational complexity **
+* $ O (NumberOfNodes + NumberOfEdges) $