79 lines
1.5 KiB
C++
79 lines
1.5 KiB
C++
|
/**
|
|||
|
|
* File: recursion.cpp
|
|||
|
|
* Created Time: 2023-08-24
|
|||
|
|
* Author: krahets (krahets@163.com)
|
|||
|
|
*/
|
|||
|
|
|
|||
|
|
#include "../utils/common.hpp"
|
|||
|
|
|
|||
|
|
/* <20>ݹ<EFBFBD> */
|
|||
|
|
int recur(int n) {
|
|||
|
|
// <20><>ֹ<EFBFBD><D6B9><EFBFBD><EFBFBD>
|
|||
|
|
if (n == 1)
|
|||
|
|
return 1;
|
|||
|
|
// <20>ݣ<EFBFBD><DDA3>ݹ<EFBFBD><DDB9><EFBFBD><EFBFBD><EFBFBD>
|
|||
|
|
int res = recur(n - 1);
|
|||
|
|
// <20>飺<EFBFBD><E9A3BA><EFBFBD>ؽ<EFBFBD><D8BD><EFBFBD>
|
|||
|
|
return n + res;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* ʹ<>õ<EFBFBD><C3B5><EFBFBD>ģ<EFBFBD><C4A3><EFBFBD>ݹ<EFBFBD> */
|
|||
|
|
int forLoopRecur(int n) {
|
|||
|
|
// ʹ<><CAB9>һ<EFBFBD><D2BB><EFBFBD><EFBFBD>ʽ<EFBFBD><CABD>ջ<EFBFBD><D5BB>ģ<EFBFBD><C4A3>ϵͳ<CFB5><CDB3><EFBFBD><EFBFBD>ջ
|
|||
|
|
stack<int> stack;
|
|||
|
|
int res = 0;
|
|||
|
|
// <20>ݣ<EFBFBD><DDA3>ݹ<EFBFBD><DDB9><EFBFBD><EFBFBD><EFBFBD>
|
|||
|
|
for (int i = n; i > 0; i--) {
|
|||
|
|
// ͨ<><CDA8><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ջ<EFBFBD><D5BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģ<EFBFBD>⡰<EFBFBD>ݡ<EFBFBD>
|
|||
|
|
stack.push(i);
|
|||
|
|
}
|
|||
|
|
// <20>飺<EFBFBD><E9A3BA><EFBFBD>ؽ<EFBFBD><D8BD><EFBFBD>
|
|||
|
|
while (!stack.empty()) {
|
|||
|
|
// ͨ<><CDA8><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ջ<EFBFBD><D5BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģ<EFBFBD>⡰<EFBFBD>顱
|
|||
|
|
res += stack.top();
|
|||
|
|
stack.pop();
|
|||
|
|
}
|
|||
|
|
// res = 1+2+3+...+n
|
|||
|
|
return res;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* β<>ݹ<EFBFBD> */
|
|||
|
|
int tailRecur(int n, int res) {
|
|||
|
|
// <20><>ֹ<EFBFBD><D6B9><EFBFBD><EFBFBD>
|
|||
|
|
if (n == 0)
|
|||
|
|
return res;
|
|||
|
|
// β<>ݹ<EFBFBD><DDB9><EFBFBD><EFBFBD><EFBFBD>
|
|||
|
|
return tailRecur(n - 1, res + n);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* 쳲<><ECB3B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>У<EFBFBD><D0A3>ݹ<EFBFBD> */
|
|||
|
|
int fib(int n) {
|
|||
|
|
// <20><>ֹ<EFBFBD><D6B9><EFBFBD><EFBFBD> f(1) = 0, f(2) = 1
|
|||
|
|
if (n == 1 || n == 2)
|
|||
|
|
return n - 1;
|
|||
|
|
// <20>ݹ<EFBFBD><DDB9><EFBFBD><EFBFBD><EFBFBD> f(n) = f(n-1) + f(n-2)
|
|||
|
|
int res = fib(n - 1) + fib(n - 2);
|
|||
|
|
// <20><><EFBFBD>ؽ<EFBFBD><D8BD><EFBFBD> f(n)
|
|||
|
|
return res;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
/* Driver Code */
|
|||
|
|
int main() {
|
|||
|
|
int n = 5;
|
|||
|
|
int res;
|
|||
|
|
|
|||
|
|
res = recur(n);
|
|||
|
|
cout << "\n<EFBFBD>ݹ麯<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͽ<EFBFBD><EFBFBD><EFBFBD> res = " << res << endl;
|
|||
|
|
|
|||
|
|
res = forLoopRecur(n);
|
|||
|
|
cout << "\nʹ<EFBFBD>õ<EFBFBD><EFBFBD><EFBFBD>ģ<EFBFBD><EFBFBD><EFBFBD>ݹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͽ<EFBFBD><EFBFBD><EFBFBD> res = " << res << endl;
|
|||
|
|
|
|||
|
|
res = tailRecur(n, 0);
|
|||
|
|
cout << "\nβ<EFBFBD>ݹ麯<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͽ<EFBFBD><EFBFBD><EFBFBD> res = " << res << endl;
|
|||
|
|
|
|||
|
|
res = fib(n);
|
|||
|
|
cout << "\n쳲<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>еĵ<EFBFBD> " << n << " <20><>Ϊ " << res << endl;
|
|||
|
|
|
|||
|
|
return 0;
|
|||
|
|
}
|