Language: C++

#include<stdio.h>
#define MAX 100000
#define SENTINEL 2000000000
struct Card{
	char suit;
	int value;
};

int A[MAX], n;
struct Card L[MAX / 2 + 2], R[MAX / 2 + 2];

void merge(struct Card A[],int n, int left, int mid, int right){
	int n1 = mid - left;
	int n2 = right - mid;
	int i,j,k;
	for (i = 0; i < n1; i++){
		L[i] = A[left + i];
	}
	for (i = 0; i < n2; i++){
		R[i] = A[mid + i];
	}
	L[n1].value = SENTINEL;
	R[n2].value = SENTINEL;
	i = 0;
	j = 0;
	for (k = left; k < right; k++){
		if (L[i].value <= R[j].value){
			A[k] = L[i];
			i = i + 1;
		}
		else{
			A[k] = R[j];
			j = j + 1;
		}
	}
}

void mergeSort(struct Card A[], int n, int left, int right){
	int mid;
	if (left + 1 < right){
		mid = (left + right) / 2;
		mergeSort(A, n, left, mid);
		mergeSort(A, n, mid, right);
		merge(A, n, left, mid, right);
	}
}

int partition(int p, int r){
	struct Card tmp,x = A[r];
	int j,i = p - 1;
	for (j = p; j < r; j++){
		if (A[j].value <= x.value){
			i = i + 1;
			tmp = A[i];
			A[i] = A[j];
			A[j] = tmp;
		}
	}
	tmp = A[i+1];
	A[i+1] = A[r];
	A[r] = tmp;
	return i + 1;
}

void quickSort(struct Card A[], int n, int p, int r){
	int q;
	if (p < r){
		q = partition(A, n, p, r);
		quickSort(A, n, p, q - 1);
		quickSort(A, n, q + 1, r);
	}
}

int main(){
	int i,j,v;
	char S[10];
	struct Card A[MAX],B[MAX];
	scanf("%d", &n);
	for (i = 0; i < n; i++){
		scanf("%s %d", S, &v);
		A[i].suit = B[i].suit = S[0];
		A[i].value = B[i].value = v;
	}
	quickSort(A, n, 0, n);
	mergeSort(B, n, 0, n - 1);
	for (i = 0; i < n; i++){
		if (A[i].suit != B[i].suit){
			stable = 0;
			break;
		}
	}
	if (stable == 1){
		printf("Stable\n");
	}
	else{
		parintf("Not Stable\n");
	}
	for (i = 0; i < n; i++){
		printf("%c %d\n", B[i].suit, B[i].value);
	}
	return 0;
}

Compiler output:
a.cc: In function 'int partition(int, int)':
a.cc:49:32: error: conversion from 'int' to non-scalar type 'Card' requested
   49 |         struct Card tmp,x = A[r];
      |                             ~~~^
a.cc:52:26: error: request for member 'value' in 'A[j]', which is of non-class type 'int'
   52 |                 if (A[j].value <= x.value){
      |                          ^~~~~
a.cc:54:34: error: no match for 'operator=' (operand types are 'Card' and 'int')
   54 |                         tmp = A[i];
      |                                  ^
a.cc:4:8: note: candidate: 'constexpr Card& Card::operator=(const Card&)'
    4 | struct Card{
      |        ^~~~
a.cc:4:8: note:   no known conversion for argument 1 from 'int' to 'const Card&'
a.cc:4:8: note: candidate: 'constexpr Card& Card::operator=(Card&&)'
a.cc:4:8: note:   no known conversion for argument 1 from 'int' to 'Card&&'
a.cc:56:32: error: cannot convert 'Card' to 'int' in assignment
   56 |                         A[j] = tmp;
      |                                ^~~
      |                                |
      |                                Card
a.cc:59:20: error: no match for 'operator=' (operand types are 'Card' and 'int')
   59 |         tmp = A[i+1];
      |                    ^
a.cc:4:8: note: candidate: 'constexpr Card& Card::operator=(const Card&)'
    4 | struct Card{
      |        ^~~~
a.cc:4:8: note:   no known conversion for argument 1 from 'int' to 'const Card&'
a.cc:4:8: note: candidate: 'constexpr Card& Card::operator=(Card&&)'
a.cc:4:8: note:   no known conversion for argument 1 from 'int' to 'Card&&'
a.cc:61:16: error: cannot convert 'Card' to 'int' in assignment
   61 |         A[r] = tmp;
      |                ^~~
      |                |
      |                Card
a.cc: In function 'void quickSort(Card*, int, int, int)':
a.cc:68:31: error: invalid conversion from 'Card*' to 'int' [-fpermissive]
   68 |                 q = partition(A, n, p, r);
      |                               ^
      |                               |
      |                               Card*
a.cc:68:30: error: too many arguments to function 'int partition(int, int)'
   68 |                 q = partition(A, n, p, r);
      |                     ~~~~~~~~~^~~~~~~~~~~~
a.cc:48:5: note: declared here
   48 | int partition(int p, int r){
      |     ^~~~~~~~~
a.cc: In function 'int main()':
a.cc:88:25: error: 'stable' was not declared in this scope; did you mean 'mutable'?
   88 |                         stable = 0;
      |                         ^~~~~~
      |                         mutable
a.cc:92:13: error: 'stable' was not declared in this scope; did you mean 'mutable'?
   92 |         if (stable == 1){
      |             ^~~~~~
      |             mutable
a.cc:96:17: error: 'parintf' was not declared in this scope; did you mean 'printf'?
   96 |                 parintf("Not Stable\n");
      |                 ^~~~~~~
      |                 printf