Given a binary tree, print all root-to-leaf paths

For the below example tree, all root-to-leaf paths are:
10 –> 8 –> 3
10 –> 8 –> 5
10 –> 2 –> 2


         10

     8            2

3        5    2


Sol:

Algorithm:
Use a path array path[] to store current root to leaf path. Traverse from root to all leaves in top-down fashion. While traversing, store data of all nodes in current path in array path[]. When we reach a leaf node, print the path array.

/*Given a binary tree, print out all of its root-to-leaf

 paths, one per line. Uses a recursive helper to do the work.*/

void printPaths(TreeNode T)

{

  int path[1000];

  printPathsRecur(T, path, 0);

}

 

/* Recursive helper function -- given a node, and an array containing

 the path from the root node up to but not including this node,

 print out all the root-leaf paths.*/

void printPathsRecur(TreeNode T, int path[], int pathLen)

{

  if (node==NULL)

    return;

 

  /* append this node to the path array */

  path[pathLen] = T.data;

  pathLen++;

 

  /* it's a leaf, so print the path that led to here  */

  if (T.left==NULL && T.right==NULL)

  {

    printArray(path, pathLen);

  }

  else

  {

    /* otherwise try both subtrees */

    printPathsRecur(T.left, path, pathLen);

    printPathsRecur(T.right, path, pathLen);

  }

}