diff --git a/README.md b/README.md
index fbf0de9..0fa8e8f 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,99 @@
-# 625
+二叉树
+#include <vector>
+#include <string>
+#include <stdlib.h>
+using namespace std;
+typedef int ElemType;
+typedef struct node
+{
+	ElemType data;				//数据元素
+	struct node* lchild;		//指向左孩子结点
+	struct node* rchild;		//指向右孩子结点
+} BTNode;						//二叉链结点类型
 
+BTNode* CreateBTree(ElemType a[], ElemType b[], int n)
+//对应例2.8的算法由先序序列a[0..n-1]和中序序列b[0..n-1]建立二叉链
+{
+    int k;
+    if (n <= 0) return NULL;
+    ElemType root = a[0];			//根结点值
+    BTNode* bt = (BTNode*)malloc(sizeof(BTNode));
+    bt->data = root;
+    for (k = 0; k < n; k++) //在b中查找b[k]=root的根结点
+        if (b[k] == root)
+            break;
+    bt->lchild = CreateBTree(a + 1, b, k);    //递归创建左子树
+    bt->rchild = CreateBTree(a + k + 1, b + k + 1, n - k - 1);  //递归创建右子树
+    return bt;
+}
+
+void DispBTree(BTNode* bt)
+//采用括号表示输出二叉链bt
+{
+    if (bt != NULL)
+    {
+        printf("%d", bt->data);
+        if (bt->lchild != NULL || bt->rchild != NULL)
+        {
+            printf("(");		             //有孩子结点时才输出(
+                DispBTree(bt->lchild);	             //递归处理左子树
+                if (bt->rchild != NULL) printf(",");	//有右孩子结点时才输出,
+                DispBTree(bt->rchild);	             //递归处理右子树
+                printf(")");                                      //有孩子结点时才输出)
+        }
+    }
+}
+
+void DestroyBTree(BTNode*& bt)
+//释放以bt为根结点的二叉树
+{
+    if (bt != NULL)
+    {
+        DestroyBTree(bt->lchild);
+        DestroyBTree(bt->rchild);
+        free(bt);
+    }
+}
+int maxsum = 0; //全局变量:存放最大路径和。
+vector<int> maxpath;    //全局变量:存放最大路径
+void Findmaxpath(BTNode* bt, vector <int > apath, int asum)
+//求根结点到叶结点的路径和最大的路径
+{
+    if (bt == NULL)    //空树直接返回
+        return;
+    apath.push_back(bt->data); asum += bt->data;    //bt结点加入apath
+    asum += bt->data;  //累计a路径和。
+    if (bt->lchild == NULL && bt->rchild == NULL) //bt结点为叶结点
+    {
+        if (asum - maxsum)
+        {
+            maxsum = asum;
+            maxpath.clear();
+            maxpath = apath;
+        }
+    }
+    Findmaxpath(bt->lchild, apath, asum); //在左子树中查找
+    Findmaxpath(bt->rchild, apath, asum); //在右子树中查找
+}
+int main()
+{
+    BTNode* bt;
+    ElemType a[] = { 5,2,3,4,1,6 };
+    ElemType b[] = { 2,3,5,1,4,6 };
+    int n = sizeof(a)/sizeof(a[0]);
+    bt = CreateBTree(a,b,n); 
+    printf("实验结果:\n");
+    printf("二叉树bt:"); 
+    DispBTree(bt); 
+    printf("'in");
+    printf("最大路径");
+    vector<int> apath;
+    int asum = 0;
+    Findmaxpath(bt,apath,asum); 
+    printf("路径和: % d，路径 : ",maxsum);
+    for (int i=0;i < maxpath.size();i++)
+        printf("%d ",maxpath[i]);
+    printf("\n");
+    printf("销毁树bt\n");
+    DestroyBTree(bt);
+}
\ No newline at end of file