diff --git a/1660_n+/Readme.md b/1660_n+/Readme.md
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+# 标题
+
+* 内容
\ No newline at end of file
diff --git a/1660_n+/doc/Readme.md b/1660_n+/doc/Readme.md
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+# 		『入门』（递归专题）求累加和
+[问题描述]  
+
+教学案例，必须使用递归函数完成求解！  
+
+　　编程求解下列式子的值：s=1+2+3+...+n。  
+
+[输入格式]  
+　　一行，只有一个整数n。(1 <= n <= 1000)  
+
+[输出格式]  
+　　1个整数，即s的值。  
+
+[输入样例]  
+100  
+
+[输出样例]  
+5050  
diff --git a/1660_n+/main.cpp b/1660_n+/main.cpp
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+//阶加（超小）
+#include <iostream>
+using namespace std;
+long long dg(long long n){
+    if(n==1){
+        return 1;
+    }
+    return n+dg(n-1);
+}
+int main()
+{
+    int n;
+    cin>>n;
+    cout<<dg(n);
+}
diff --git a/1660_n+/main.exe b/1660_n+/main.exe
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Binary files /dev/null and b/1660_n+/main.exe differ
diff --git a/1660_n+/test/in.txt b/1660_n+/test/in.txt
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+1
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diff --git a/1660_n+/test/in2.txt b/1660_n+/test/in2.txt
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+++ b/1660_n+/test/in2.txt
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+100
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diff --git a/1660_n+/test/in3.txt b/1660_n+/test/in3.txt
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+1000
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diff --git a/1660_n+/test/out.txt b/1660_n+/test/out.txt
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+## z:\Chao\src\1660_n+\test\in.txt 
+2020/04/24 周五 13:47:20.56 
+1
+-----------------------------------------------
+Process exited after 160 ms with return value 0
+
+## z:\Chao\src\1660_n+\test\in2.txt 
+2020/04/24 周五 13:47:20.56 
+5050
+-----------------------------------------------
+Process exited after 80 ms with return value 0
+
+## z:\Chao\src\1660_n+\test\in3.txt 
+2020/04/24 周五 13:47:20.56 
+500500
+-----------------------------------------------
+Process exited after 80 ms with return value 0
+