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update 3 to the right solution

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juan 2021-10-12 20:24:51 +08:00
parent 38a17714e4
commit dbff279288
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2 changed files with 23 additions and 43 deletions
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27
pset3/3-sum-problem.c
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@ -1,27 +0,0 @@
// Try to use recursion to solve this problem.
#include <stdio.h>
// function prototypes.
unsigned long long int sum(unsigned long long int n);
int main(void) {
// Initialize variables and get input from user.
unsigned long long int num;
scanf("%lld", &num);
// Print values
printf("%lld\n", sum(num));
return 0;
}
unsigned long long int sum(unsigned long long int n) {
if (n == 1 || n == 2) { // Case 1: n is 1 or 2
return 0;
} else { // Case 2: n is not
return n * (n - 1) * (n - 2) + sum(n - 1);
}
}

39
pset3/3-sum.c
View file

@ -1,24 +1,31 @@
// Try to use recursion to solve this problem.
#include <stdio.h>
// function prototypes.
unsigned long long int sum(unsigned long long int n);
int main(void) {
// Initialize variables and get input
long long sum = 0;
long long n;
scanf("%lld", &n);
// if n is smaller than 3
if (n < 3) {
printf("0\n");
return 0;
}
// Initialize variables and get input from user.
unsigned long long int num;
scanf("%lld", &num);
// Iterate through all
for (long long i = 3; i <= n; i++) {
sum += i * (i - 1) * (i - 2);
}
// Print the result
printf("%lld\n", sum);
// Calculate the sum of the numbers. (Can be optimized.)
unsigned long long int num1 = 0;
for (int i = 1; i <= num; i++) {
num1 += sum(i);
}
printf("%lld\n", num1);
return 0;
}
unsigned long long int sum(unsigned long long int n) {
if (n == 1 || n == 2) { // Case 1: n is 1 or 2
return 0;
} else { // Case 2: n is not
return n * (n - 1) * (n - 2) + sum(n - 1);
}
}