從樹的根結點開始往下訪問一直到葉結點所經過的所有結點形成一條路徑。
打印出和與輸入整數相等的所有路徑。
例如 輸入整數22和如下二元樹
則打印出兩條路徑：10, 12和10, 5, 7。
先序遍歷樹即可得到結果。
算法: FindPath(BTree * root,int sum,int target,Stack * s) 用來計算，sum為棧中的元素的和，target為目標值。
到達一個節點之后計算當前節點和sum的和，如果為target，輸出路徑返回，如果大于target，則直接返回，如果小于，則將當前節點的值入棧，更新sum的值，繼續遍歷，遍歷完成之后，也就是從當前節點返回的時候，將其從棧中彈出，更新sum
代碼如下（GCC編譯通過）：
#include "stdio.h"#include "stdlib.h"#define MAXSIZE 8 typedef struct node{ int data; struct node * left; struct node * right;}BTree; typedef struct { int top; int data[MAXSIZE];}Stack; BTree * CreatTree(int a[],int n);void Iorder(BTree * root);void Porder(BTree * root);void FindPath(BTree * root,int sum,int target,Stack * stack);void InitStack(Stack * stack);void Push(Stack * s,int val);int Pop(Stack *s); int main(void){ int array[MAXSIZE] = {5,3,8,7,2,4,1,9},target; BTree * root; Stack stack; target = 12; root = CreatTree(array,MAXSIZE); InitStack(&stack); printf("二叉樹內元素升序排列："); Iorder(root); printf("/n"); printf("目標值：%d,路徑：",target); FindPath(root,0,target,&stack); printf("/n"); return 0;} //根據數組生成二叉排序樹BTree * CreatTree(int a[],int n){ BTree * root ,*p,*cu,*pa; int i; root = (BTree *)malloc(sizeof(BTree)); root->data = a[0]; root->left = root->right =NULL; for(i=1;i<n;i++) { p = (BTree *)malloc(sizeof(BTree)); p->data = a[i]; p->left = p->right =NULL; cu = root; while(cu) { pa = cu; if(cu->data > p->data) cu = cu->left; else cu = cu->right; } if(pa->data > p->data) pa->left = p; else pa->right = p; } return root;} //中根遍歷，打印二叉樹void Iorder(BTree * root){ if(root) { Iorder(root->left); printf("%3d",root->data); Iorder(root->right); }} //尋找路徑void FindPath(BTree * root,int sum,int target,Stack * s){ int i; if(!root) return ; if(sum + root->data == target) { Push(s,root->data); for(i = 0;i<s->top;i++) printf("%3d",s->data[i]); return; } else if(sum + root->data > target) { return; } else { Push(s,root->data); sum += root->data; FindPath(root->left,sum,target,s); FindPath(root->right,sum,target,s); sum -= root->data; Pop(s); }} //初始化棧void InitStack(Stack * s){ s->top = 0;} //入棧void Push(Stack *s,int val){ if(s->top == MAXSIZE) { printf("棧滿，無法入棧！/n"); return; } s->data[(s->top)++] = val; } //出棧int Pop(Stack *s){ if(s->top == 0) { printf("棧空，無法出棧!/n"); return; } return s->data[--(s->top)];}
