PHP inputs a binary tree and a number N, which requires finding the path and all the paths for N.

1 <? PHP 2 # input a binary tree and a number n. It is required to find the path and all the paths for n. 3 4 class node {5 Public $ DATA = NULL; 6 Public $ parent = NULL; 7 public $ left = NULL; 8 Public $ right = NULL; 9} 10 11 # use an array to construct a Complete Binary Tree 12 function build_cbtree ($) {13 $ root = new node (); 14 $ root-> DATA = $ A [0]; 15 16 for ($ I = 1; $ I <count ($ A); $ I ++) {17 $ node = new node (); 18 $ node-> DATA = $ A [$ I]; 19 insert_node ($ root, $ node); 20} 21 22 return $ root; 23} 24 25 # insert completely two Function insert_node ($ root, $ inode) {27 # retrieve the node in the ascending order of the tree until the first left and right subnodes are found, insert 28 $ queue = array (); 29 array_unshift ($ queue, $ root); 30 31 While (! Empty ($ Queue) {32 $ cNode = array_pop ($ Queue); 33 if ($ cNode-> left = NULL) {34 $ cNode-> left = $ inode; 35 $ inode-> parent = $ cNode; 36 return $ root; 37} else {38 array_unshift ($ queue, $ cNode-> left ); 39} 40 if ($ cNode-> right = NULL) {41 $ cNode-> right = $ inode; 42 $ inode-> parent = $ cNode; 43 return $ root; 44} else {45 array_unshift ($ queue, $ cNode-> right); 46} 47} 48 49 return $ root; 50} 51 52 # tree breadth first traversal 53 F Unction bf_traverse ($ root) {54 $ queue = array (); 55 array_unshift ($ queue, $ root); 56 57 while (! Empty ($ Queue) {58 $ cNode = array_pop ($ Queue); 59 echo $ cNode-> data. ""; 60 if ($ cNode-> left! = NULL) array_unshift ($ queue, $ cNode-> left); 61 if ($ cNode-> right! = NULL) array_unshift ($ queue, $ cNode-> right); 62} 63 64 echo "<br>"; 65} 66 67 function get_paths ($ root, $ paths, $ sum) {68 if ($ root! = NULL) {69 $ sum-= $ root-> data; 70 $ paths [] = $ root-> data; 71 72 if ($ sum> 0) {73 # continue recursion 74 # Here paths is a value transfer call, so you can calculate multiple paths without affecting 75 if ($ root-> left! = NULL) get_paths ($ root-> left, $ paths, $ sum); 76 if ($ root-> right! = NULL) get_paths ($ root-> right, $ paths, $ sum); 77} else if ($ sum = 0) {78 # output path 79 foreach ($ paths as $ Val) {80 echo $ Val. ""; 81} 82 echo "<br>"; 83} 84} 85} 86 87 $ A = array (9, 8, 7, 6, 8, 4, 3, 2, 1); 88 $ root = build_cbtree ($ A); 89 bf_traverse ($ root); # breadth first traversal 90 $ B = array (); 91 get_paths ($ root, $ B, 25); # The output path is 92 for 25?>

9 8 7 6 8 4 3 2 1
9 8 6 2
9 8 8