3
[plus1(3) output]Begin invoke plus1(3) [plus1(3) output]I want to calculate plus1(3), require 3 and the value of plus1(2),so I need to invoke plus1(2) [plus1(2) output]Begin invoke plus1(2) [plus1(2) output]I want to calculate plus1(2), require 2 and the value of plus1(1),so I need to invoke plus1(1) [plus1(1) output]Begin invoke plus1(1) [plus1(1) output]return plus1(1) = 1 [plus1(2) output]I got the value of plus1(1), and plus it to 2then return3 [plus1(3) output]I got the value of plus1(2), and plus it to 3then return6 6
#include <cstdio> #include <iostream> #include <cmath> #include <string> #include <cstring> #include <algorithm> #include <queue> using namespace std; #define ll long long int n, sum; int plu(int a) { printf("[plus1(%d) output]Begin invoke plus1(%d)\n", a, a); if(a != 1) { printf("[plus1(%d) output]I want to calculate plus1(%d), require %d and the value of plus1(%d),so I need to invoke plus1(%d)\n", a, a, a, a-1, a-1); sum = a+plu(a-1); printf("[plus1(%d) output]I got the value of plus1(%d), and plus it to %dthen return%d\n", a, a-1, a, sum); return sum; } else { printf("[plus1(1) output]return plus1(1) = 1\n"); return 1; } } int main() { scanf("%d", &n); plu(n); printf("%d\n", sum); }
原文：https://www.cnblogs.com/RootVount/p/10889921.html