Quick Test CLI provides full support for GNU C with automatic compilation and execution of your competitive programming solutions.
File Extension
C files must use the .c extension:
Compilation
C files are compiled using gcc with the following command:
gcc -std=gnu11 -lm main.c -o .qt/main
Compilation Flags
-std=gnu11 - Uses GNU C11 standard (C11 with GNU extensions)-lm - Links the math library (required for functions like sqrt, pow, etc.)-o .qt/main - Outputs the compiled binary to .qt/main
The -lm flag is essential if you use any mathematical functions from <math.h>.
Execution
After compilation, the binary is executed with:
Example Code
Here’s a typical C solution for competitive programming:
#include <stdio.h>
#include <string.h>
#define N 100001
int a[N];
int max(int a, int b) { return a > b ? a : b; }
int min(int a, int b) { return a < b ? a : b; }
int main() {
int n;
scanf("%d", &n);
for(int i = 0; i < n; ++i)
scanf("%d", &a[i]);
int best = 0, sum = 0;
for (int i = 0; i < n; i++) {
sum = max(a[i], sum + a[i]);
best = max(best, sum);
}
printf("%d\n", best);
return 0;
}
Usage with Quick Test
Compare Mode (cmp)
Compare your solution against a brute-force correct solution:
quicktest cmp --target-file=main.c --correct-file=correct.c --gen-file=gen.c
Stress Testing Mode
Test your solution’s performance:
quicktest stress --target-file=main.c --gen-file=gen.c --tout 1000 --tc 1000
Checker Mode
For problems with multiple valid answers:
quicktest check --target-file=main.c --checker-file=checker.c --gen-file=gen.c
Requirements
You must have gcc (GNU Compiler Collection) installed on your system to compile C files.
#include <stdio.h> // Standard I/O (printf, scanf)
#include <stdlib.h> // Memory allocation, random numbers
#include <string.h> // String manipulation
#include <math.h> // Mathematical functions
#include <stdbool.h> // Boolean type
#include <limits.h> // Integer limits (INT_MAX, INT_MIN)
Remember to use -lm flag when compiling if you include <math.h>.
// Single integer
int n;
scanf("%d", &n);
// Multiple integers
int a, b, c;
scanf("%d %d %d", &a, &b, &c);
// Array
int arr[100];
for (int i = 0; i < n; i++) {
scanf("%d", &arr[i]);
}
// String
char s[1000];
scanf("%s", s); // Note: no & for strings
Writing Output
// Integer
printf("%d\n", x);
// Long long
printf("%lld\n", x);
// Multiple values
printf("%d %d\n", a, b);
// Formatted
printf("%.2f\n", pi); // 2 decimal places
Helper Functions
C doesn’t have built-in min/max macros, so define them:
int max(int a, int b) { return a > b ? a : b; }
int min(int a, int b) { return a < b ? a : b; }
long long maxll(long long a, long long b) { return a > b ? a : b; }
long long minll(long long a, long long b) { return a < b ? a : b; }
#define max(a, b) ((a) > (b) ? (a) : (b))
#define min(a, b) ((a) < (b) ? (a) : (b))
When using macros, always wrap parameters in parentheses to avoid operator precedence issues.
Memory Management
Dynamic Arrays
// Allocate
int *arr = (int*)malloc(n * sizeof(int));
// Use
for (int i = 0; i < n; i++) {
arr[i] = i;
}
// Free (important!)
free(arr);
For competitive programming, you can often use static arrays with a large size instead of dynamic allocation for simplicity.
C vs C++
While C and C++ are similar, there are key differences:
- C requires explicit type casting for malloc
- No STL containers (vector, map, set, etc.)
- Must use
scanf/printf instead of cin/cout
- C99/C11 added features like
bool, inline variable declarations
C compiled with gcc produces highly optimized native code with excellent performance, often comparable to or better than C++.
- Linux: Full support
- Windows: Full support
- macOS: Full support