diff --git a/test99-5-1.cpp b/test99-5-1.cpp
new file mode 100644
index 0000000..2a09ce9
--- /dev/null
+++ b/test99-5-1.cpp
@@ -0,0 +1,65 @@
+// 树形结构的前中后序遍历，以及bfs层级遍历
+#include<bits/stdc++.h>
+using namespace std;
+const int N = 20;
+int ls[N], rs[N];
+// 先序遍历
+void dfs1(int x){
+    cout << x << ' ';
+    if(ls[x]) dfs1(ls[x]);
+    if(rs[x]) dfs1(rs[x]);
+}
+
+// 中序遍历
+void dfs2(int x){
+    if(ls[x]) dfs2(ls[x]);
+    cout << x << ' ';
+    if(rs[x]) dfs2(rs[x]);
+}
+
+// 后序遍历
+void dfs3(int x){
+    if(ls[x]) dfs3(ls[x]);
+    if(rs[x]) dfs3(rs[x]);
+    cout << x << ' ';
+}
+
+// 层序遍历
+void bfs(){
+    queue<int> q;
+    q.push(1);
+    while(q.size()){
+        int x = q.front(); q.pop();
+        cout << x << ' ';
+        if(ls[x]) q.push(ls[x]);
+        if(rs[x]) q.push(rs[x]);
+    }
+}
+
+int main(){
+    int n; cin >> n;
+    for(int i = 1; i <= n; i++) cin >> ls[i] >> rs[i];
+    dfs1(1); cout << endl;
+    dfs2(1); cout << endl;
+    dfs3(1); cout << endl;
+    bfs(); cout << endl;
+    return 0;
+}
+/* test samples
+10
+2 3
+4 5
+6 7
+8 0
+0 9
+0 0
+10 0
+0 0
+0 0
+0 0
+out:
+1 2 4 8 5 9 3 6 7 10
+8 4 2 5 9 1 6 3 10 7
+8 4 9 5 2 6 10 7 3 1
+1 2 3 4 5 6 7 8 9 10
+*/