renamed dfs.md as readme.md and added gif

Author: imVivekGupta

Competitive Coding/Graphs/Graph_Search/DepthFIrstSearch/DFS.md

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+## Depth-first search (DFS)
+ An algorithm for traversing or searching tree or graph data structures. One starts at the root (selecting some arbitrary node as the root in the case of a graph) and explores as far as possible along each branch before backtracking
+
+----
+![](https://upload.wikimedia.org/wikipedia/commons/7/7f/Depth-First-Search.gif)
+----
+This is the algorithm for Depth First Search in a given graph.
+
+* We take a starting vertex , and push all its adjacent vertexes in a stack.
+* Now we pop an element from a stack and push all its vertexes in the stack , and we also mark down these vertexes as visited.
+* After executing the code, we will get the vertex visited in a depth first manner.
+
+[more info](https://en.wikipedia.org/wiki/Depth-first_search)