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Here is my C++ code for counting sort algorithm , there is no errors as well as no warnings but when I want to execute it it's give me "Counting.exe has stopped working" I think it is a run time error.
void Counting_sort()
{
int A[]={5,15,20,30,40,8,36,25,96,15,40,15,96,47,20};
int k = 15 ;
int n = 15;
int i, j;
int B[15];
int C[100];
for(i = 0; i <= k; i++)
C[i] = 0;
for(j =1; j <= n; j++)
C[A[j]] = C[A[j]] + 1;
for(i = 1; i <= k; i++)
C[i] = C[i] + C[i-1];
for(j = n; j >= 1; j--)
{
B[C[A[j]]] = A[j];
C[A[j]] = C[A[j]] - 1;
}
cout << "\nThe Sorted array is : ";
for(i = 1; i <= n; i++)
cout << B[i] << " " ;
}
void main()
{
Counting_sort();
}
for(j = n; j >= 1; j--)
{
// You are accessing A[j]
}
So A[15] is a invalid access and will lead to undefined behavior.
The valid access for array A[15] is A[0] to A[14] anything other than this is array out of bound access.
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when I trying to implement the counting sort I got this error " the problem caused the program to stop working correctly Windows will close the program and notify you if a solution is available "
void CountingSort(int *A,int size) {
int SizeC = Max(A, size);
int* B = new int[size];
int* C = new int[SizeC+1];
for (int i = 0; i < SizeC; i++) {
C[i] = 0;
}
for (int i = 0; i < size; i++) {
C[A[i]]++ ;
}
for (int i = 0; i <SizeC; i++)
{
C[i] += C[i - 1];
}
for (int j = size - 1; j >= 0; j--) {
B[C[A[j]]] = A[j];
C[A[j]] --;
}
for (int i = 0; i < size; i++) {
cout << B[i] << "\t" << endl;
}
delete[] C;
delete[] B;
}
this is the error
i < SizeC and i <SizeC should be i <= SizeC. Otherwise, the elements with value SizeC won't be treated properly.
C[i] += C[i - 1]; with i = 0 will result in out-of-range read of C[-1]. The initialization of corresponding for loop should be int i = 1, not int i = 0.
The decrementing C[A[j]] --; should happen before B[C[A[j]]] = A[j];, or out-of-range write of B[size] will happen.
This program won't work well when the array A contains negative values.
Fixed code (negative values are still not supported):
void CountingSort(int *A,int size) {
int SizeC = Max(A, size);
int* B = new int[size];
int* C = new int[SizeC+1];
for (int i = 0; i <= SizeC; i++) {
C[i] = 0;
}
for (int i = 0; i < size; i++) {
C[A[i]]++ ;
}
for (int i = 1; i <= SizeC; i++)
{
C[i] += C[i - 1];
}
for (int j = size - 1; j >= 0; j--) {
C[A[j]] --;
B[C[A[j]]] = A[j];
}
for (int i = 0; i < size; i++) {
cout << B[i] << "\t" << endl;
}
delete[] C;
delete[] B;
}
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So I need help. The problem is that an int arr[5] = {0};
I know the array has the values {0,0,0,0,0} filling the whole array. At the end of the code the array must have the values {1,2,3,4,5} inside it. To solve it must use a nested for loop.
I have tried the following code
Sorry if there is an error in the way this question is formatted this is my first time and using mobile.
int arr[5] = {0};
for(int j = 1; j<6; j++)
{
for(int i = 0; i<5; i++)
{
arr[i] = j;
}
}
I don't know what the benefit of that but If you have to use nested for loop, the following is an option
int main()
{
int arr[5] = {0};
for(int j = 0; j < 5; ++j)
{
for(int i = 1; i < 2; ++i)
{
arr[j] = j+i;
}
}
for(int i{};i<5;++i) std::cout << arr[i] << ", ";
}
Or like #JaMit comment suggests
int main()
{
int arr[5] = {0};
for(int j = 0; j < 5; ++j)
{
for(int i = 0; i < j+1; ++i)
{
arr[j]++;
}
}
for(int i{};i<5;++i) std::cout << arr[i] << ", ";
}
I'm guessing your professor means you should generate the final results using only incrementation. In other words, I'm guessing you're not allowed to assign values after the int arr[5] = {0}; line (so an expression like arr[i] = j; is not allowed).
In that case, you could solve the problem as follows:
int arr[5] = {0};
for (int i = 0; i < 5; i++) {
for (int j = i; j < 5; j++) {
arr[j]++;
}
}
Now we have only used incrementation and the final result is {1, 2, 3, 4, 5}.
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I just want to know why it come the question that string subscript out of range,I have already initialized the string array.Thank you.
#include<bits/stdc++.h>
#define N 100000
using namespace std;
string s[N + 5] = {}, ss[N + 5] = { " " }, fs[N + 5] = { " " };
int main()
{
int n, x; char c;
cin >> n;
for (int i = 0; i<n; ++i)
{
for (int j = 0; j<6; ++j)
{
scanf("%c", &c);//the error comes here.
if (c == ' ') continue;
s[i] += c;
}
ss[i] = s[i] + s[i];
for (int j = 5; j >= 0; --j) fs[i][j] = s[i][5 - j];
}
int flag = 0;
for (int i = 0; i<n; ++i)
{
for (int j = 0; j<n; ++j)
{
if (i == j) continue;
if (find(s[i], fs[j]) || find(s[i], ss[j]))
{
flag = 1; break;
}
}
}
}
1) Why should I not #include <bits/stdc++.h>?
2) Avoid global variables and use std::vector when size is unknown.
3) Why is using namespace std considered bad practice?
You're getting an out of range error because of fs[i][j] accessing empty strings f[i].
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I need to find the average of the negative elements in the two-dimensional array. This is what I've got so far:
#include <iostream>
using namespace std;
int main() {
int A[3][3];
int i, j;
for(i = 0; i < 3; i++)
for(j = 0; j < 3; j++) {
cout << "\n A[" << i + 1 << "][" << j + 1 <<"]=";
cin >> A[i][j];
}
for(i = 0; i < 3; i++) {
for(j = 0; j < 3; j++)
cout << A[i][j] << "\t";
cout << "\n";
}
}
You could do it for example:
int negNumber = 0;
int sum = 0;
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 3; ++j) {
if (A[i][j] < 0) {
++negNumber; // increase negatives numbers found
sum += A[i][j]; // add to our result the number
}
}
}
sum = negNumber > 0 ? sum / negNumber : sum; // we need to check if we found at least one negative number
I hope it will help you but be careful! It will return a truncated value (an int).
the ternary operation could be difficult to undertand so you can do it:
if (negNumber > 0) {
sum /= negNumber;
}
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So to cut a long story short, I am trying to implement countsort for vector. I have some error somewhere in my code, though I think that I have followed the pseudo code pretty strictly.
The function:
void csort(vector<int>& a, vector<int>& b)
{
vector<int> c(a.size());
for(int i = 0; i <= c.size(); i++)
c[i] = 0;
for(int i = 0; i <= a.size(); i++ )
{
c[a[i]]++;
}
for(int i = 0; i <= c.size(); i++)
{
c[i]+= c[i-1];
}
for(int i = a.size(); i < 1; i--)
{
b[c[a[i]]] = a[i];
c[a[i]] =c[a[i]] -1;
}
}
The pesudo code:
let C[k] be a new array
for i = 0 to k
C[i] = 0
for j = 1 to A:length
C[A[j]] = C[A[j]] +1
for i = 1 to k
C[i] = C[i]+ C[i-1]
for j = A:length downto 1
B[C[A[j]]] = A[j]
C[A[j]] = C[A[j]] -1
The code as it is is very unreadable and error prone. In any case, what I first saw is that in the snippet below you will access c[-1] at the first iteration, thus incurring in undefined behaviour.
for (int i = 0; i <= c.size(); i++)
{
c[i] += c[i-1]; // Evaluation of c[i-1] is illegal for i == 0
}
for(int i = a.size(); i < 1; i--)
This code won't work at all.
for j = A:length downto 1
↑
To implement this pseudo code, you should do like this
for(int i(a.size()-1);i>=0;--i)
And for code like this( c[a[i]] )，you will get run-time error if a[i]<0 or a[i]>=c.size()