我正在处理来自CodeChef的问题,我需要计算n个数字的阶乘。
用户输入一个数字,用于确定执行因子计算的总数,然后输入要计算的数字。
我的问题在于乘法本身。例如,如果我有一个int == 5那么结果将是20(它将仅通过最后一个因子计算n,而不是全部计算n)
以下是问题所在:
for(int x = 0; x < _numbersToProcess.Length; x++) {// Loop throuigh Array by index
for (int y = 1; y < _numbersToProcess[x]; y++) {// Y is equal to less than index x
_result[x] = _numbersToProcess[x] * y;// Multiply x by y then add to array
}
}
外部循环定义要执行的计算量。
内部循环通过迭代_numberToProcess
的每个索引并将其乘以小于要计算的数字的每个数字来计算阶乘。
问题是因子计算会覆盖自己,
例如:
5的结果:20
但它应该是120(它会覆盖自己,直到到达最后一个乘数)
所以我尝试了以下内容:
_result[x] = _numbersToProcess[x] *= y;
这显然与_numbersToProcess[x] = _numbersToProcess[x] * y;
但这给出了完全不同的结果:
如果我们再次输入5,那么这将导致输出-1899959296。
我知道我可以轻松地从其他提交中复制和粘贴,但我想知道为什么我的方法不会产生正确的输出。
以下是完整的方法:
int _numbers = int.Parse(Console.ReadLine());// Get number of ints to calculate
int[] _numbersToProcess = new int[_numbers];// Array of inputs
int[] _result = new int[_numbers];
int i = 0;
while(i < _numbersToProcess.Length) {
_numbersToProcess[i] = int.Parse(Console.ReadLine());
i++;
}
for(int x = 0; x < _numbersToProcess.Length; x++) {// Loop throuigh Array by index
for (int y = 1; y < _numbersToProcess[x]; y++) {// Y is equal to less than index x
_result[x] = _numbersToProcess[x] *= y;// Multiply x by y then add to array
}
}
for (int n = 0; n < _result.Length; n++) {// Y is equal to less than index x
Console.WriteLine(_result[n]);// Write to console
}
Console.ReadLine();
答案 0 :(得分:3)
int _numbers = int.Parse(Console.ReadLine());// Get number of ints to calculate
int[] _numbersToProcess = new int[_numbers];// Array of inputs
int[] _result = new int[_numbers];
int i = 0;
while(i < _numbersToProcess.Length) {
_numbersToProcess[i] = int.Parse(Console.ReadLine());
i++;
}
for (int x = 0; x < _numbersToProcess.Length; x++)
{// Loop throuigh Array by index
int fact = 1;
for (int y = 1; y <= _numbersToProcess[x]; y++)
{// Y is equal to less than index x
fact = fact*y;
}
_result[x] = fact;
}
for (int n = 0; n < _result.Length; n++) {// Y is equal to less than index x
Console.WriteLine(_result[n]);// Write to console
}
Console.ReadLine();
问题在于你的内在循环。在这里,你总是,重写结果数组。
,即y = 5; 内部循环执行5次。
iteration -1 :
y=1,
_numbersToProcess[5]=5
_result[x]=5
iteration -2 :
y=2,
_numbersToProcess[5]=10
_result[x]=10
iteration -3 :
y=3,
_numbersToProcess[5]=30
_result[x]=30
.
.
.
.
.
因此,当你的_numbertoprocess [5]正在改变时它会进行12次迭代,并且一旦达到小于0就会停止,即-1899959296。
iteration 12:
_numbertoprocess[5] = -1899959296.
即您每次都在内部for循环中更改numbertoprocess。
您可以通过添加
来验证它Console.WriteLine(y);
Console.WriteLine(_numbersToProcess[x]);
Console.WriteLine(_result[x]);
在你的内部for循环中。
答案 1 :(得分:1)
for (int y = 1; y < _numbersToProcess[x]; y++) {// Y is equal to less than index x
_result[x] = _numbersToProcess[x] *= y;// Multiply x by y then add to array
}
在循环条件y < _numberToProcess[x];
中。它在y
和_numberToProcess[x]
数组值
我认为您应该将循环条件编辑为y < x
很幸运。
答案 2 :(得分:0)
这里我使用的是递归函数factorial
/* Factorial function*/
int factorial (int n)
{
return (n*factorial(n-1))
}
int _numbers = int.Parse(Console.ReadLine());// Get number of ints to calculate
int[] _numbersToProcess = new int[_numbers];// Array of inputs
int[] _result = new int[_numbers];
int i = 0;
while(i < _numbersToProcess.Length) {
_numbersToProcess[i] = int.Parse(Console.ReadLine());
i++;
}
for(int x = 0; x < _numbersToProcess.Length; x++) {// Loop throuigh Array by index
_result[x] = factorial(_result[x])// Multiply x by y then add to array
}
}
for (int n = 0; n < _result.Length; n++) {// Y is equal to less than index x
Console.WriteLine(_result[n]);// Write to console
}
Console.ReadLine();
答案 3 :(得分:-1)
#include <stdio.h>
int main()
{
int c, n, fact = 1;
printf("Enter a number to calculate it's factorial\n");
scanf("%d", &n);
for (c = 1; c <= n; c++)
fact = fact * c;
printf("Factorial of %d = %d\n", n, fact);
return 0;
}
答案 4 :(得分:-2)
检查一下这可能会有所帮助......
#include <stdio.h>
#include <stdlib.h>
long f(int n) {
if (n==0) return 1;
else return n * f(n-1);
}
int main(int argc, char *argv[]) {
long *factorials;
int *inputs;
int n;
printf("Enter number n = ");
scanf("%d", &n);
factorials = (long *) malloc(n*sizeof(long));
inputs = (int *) malloc(n*sizeof(int));
for (int i = 0; i < n; i++) {
long k;
printf("Enter %d number = ", i + 1);
scanf("%ld", &k);
inputs[i] = k;
factorials[i] = f(k);
}
for (int i = 0; i < n; i++) {
printf("Factorial for %d = %ld\n", inputs[i], factorials[i]);
}
return 0;
}