Line 15: Line 15:
 
{
 
{
 
int i, j, p;
 
int i, j, p;
if(start >= end-1)
+
if(start >= end)
 
{
 
{
 
return;
 
return;
 
}
 
}
i = p = start, j = end-1;
+
i = p = start, j = end;
 
while(i < j)
 
while(i < j)
 
{
 
{
while(a[i] <= a[p] && i < end-1)
+
while(a[i] <= a[p] && i < end)
 
i++;
 
i++;
 
while(a[j] > a[p])
 
while(a[j] > a[p])
Line 32: Line 32:
 
}
 
}
 
swap(&a[j], &a[p]);
 
swap(&a[j], &a[p]);
qsort(a, start,  j);
+
qsort(a, start,  j-1);
 
qsort(a,  j + 1, end);
 
qsort(a,  j + 1, end);
 
}
 
}
Line 58: Line 58:
 
sscanf(str, "%d", &num[i++]);  
 
sscanf(str, "%d", &num[i++]);  
 
}
 
}
qsort(num, 0, i);
+
qsort(num, 0, i-1);
 
printf("The sorted numbers are: ");
 
printf("The sorted numbers are: ");
 
printArray(num, i);
 
printArray(num, i);

Revision as of 22:50, 15 January 2014

Complexity and no. of swaps required

<syntaxhighlight lang="c">

  1. include <stdio.h>

void swap(int *a, int *b) { int temp = *a; *a = *b; *b = temp; }

void qsort(int a[], int start, int end) { int i, j, p; if(start >= end) { return; } i = p = start, j = end; while(i < j) { while(a[i] <= a[p] && i < end) i++; while(a[j] > a[p]) j--; if(i < j) { swap(&a[i], &a[j]); } } swap(&a[j], &a[p]); qsort(a, start, j-1); qsort(a, j + 1, end); }

void printArray(int a[], int n) { int i; for(i = 0; i < n; i++) { printf("%d ",a[i]); } }

int main() { char str[20]; int num[100]; int i = 0; printf("Enter the numbers to sort (. to stop): "); while(1) { scanf("%s",str); if(str[0] == '.') break; sscanf(str, "%d", &num[i++]); } qsort(num, 0, i-1); printf("The sorted numbers are: "); printArray(num, i); printf("\n"); } </syntaxhighlight>




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Complexity and no. of swaps required

<syntaxhighlight lang="c">

  1. include <stdio.h>

void swap(int *a, int *b) { int temp = *a; *a = *b; *b = temp; }

void qsort(int a[], int start, int end) { int i, j, p; if(start >= end-1) { return; } i = p = start, j = end-1; while(i < j) { while(a[i] <= a[p] && i < end-1) i++; while(a[j] > a[p]) j--; if(i < j) { swap(&a[i], &a[j]); } } swap(&a[j], &a[p]); qsort(a, start, j); qsort(a, j + 1, end); }

void printArray(int a[], int n) { int i; for(i = 0; i < n; i++) { printf("%d ",a[i]); } }

int main() { char str[20]; int num[100]; int i = 0; printf("Enter the numbers to sort (. to stop): "); while(1) { scanf("%s",str); if(str[0] == '.') break; sscanf(str, "%d", &num[i++]); } qsort(num, 0, i); printf("The sorted numbers are: "); printArray(num, i); printf("\n"); } </syntaxhighlight>




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