Please answer all parts of the question

Write an algorithm which counts the number of vertices having the same value x of a connected graph. You may directly use/call the depth-first search or breadth-first-search method without giving details of these two graph search methods. Write an algorithm which sorts the array so that for a given value x, all the elements smaller than or equal to x will be put in the left part of the array and all the elements greater than x will be put in the right part of the array although the resultant array may not be in non-decreasing order. Can Prim's algorithm find a minimal spanning tree for a given weighted connected graph of which weights may not all be positive? Justify your