43 递归的思想与应用（上）

 

原文：https://www.cnblogs.com/wanmeishenghuo/p/9677857.html参考狄泰软件相关教程

 

 

 

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#include <iostream> #include <cstring> #include "DTString.h"   using namespace std; using namespace DTLib;   unsigned int sum(unsigned int n) {     if( n > 1 )     {         return n + sum(n - 1);     }     else     {         return 1;     } }   int main() {     cout << sum(100) << endl;       return 0; }

　

 

 

 

 

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#include <iostream> #include <cstring> #include "DTString.h"   using namespace std; using namespace DTLib;   unsigned int sum(unsigned int n) {     if( n > 1 )     {         return n + sum(n - 1);     }     else     {         return 1;     } }   unsigned int fac(unsigned int n) {     if( n > 2 )     {         return fac(n - 1) + fac(n - 2);     }       if( (n == 2) || (n == 1) )     {         return 1;     }       return 0; }   int main() {     cout << sum(100) << endl;       for(int i = 1; i <= 10; i++)     {         cout << i << " : " << fac(i) << endl;     }       return 0; }

 

 

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#include <iostream> #include <cstring> #include "DTString.h"   using namespace std; using namespace DTLib;   unsigned int sum(unsigned int n) {     if( n > 1 )     {         return n + sum(n - 1);     }     else     {         return 1;     } }   unsigned int fac(unsigned int n) {     if( n > 2 )     {         return fac(n - 1) + fac(n - 2);     }       if( (n == 2) || (n == 1) )     {         return 1;     }       return 0; }   unsigned int _strlen_(const char* s) {     if( *s != '\0' )     {         return 1 + _strlen_(s+1);     }     else     {         return 0;     } }   int main() {     cout << _strlen_("Hello World") << endl;       return 0; }

　

 

 代码改进：

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unsigned int _strlen_(const char* s) {    return s ? (*s ? (1 + _strlen_(s + 1)) : 0) : 0; }

　　

小结：