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Roytangrb/poker.c

Created November 21, 2020 16:57
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Poker Hands Probabilities
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poker.c
/*
* Card Struct
* By RT
* 21 Nov, 2020
*/
#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#define DECK_SIZE 52
#define TEST_SIZE 1000000
typedef enum suit {
DIAMONDS,
CLUBS,
HEARTS,
SPADES,
} suit;
typedef struct card {
short pip; // pip value
suit s; // suit type
} card;
void init_deck(card deck[]);
void shuffle_deck(card deck[]);
void print_deck(card deck[]);
int has_pairs(int n, card hand[], int pair);
int has_x_of_a_kind(int n, card hand[], int x);
int has_full_house(int n, card hand[]);
int main(void){
srand(time(NULL));
int i = 0;
int no_pair_case = 0,
one_pair_case = 0,
two_pairs_case = 0,
has_3_of_a_kind_case = 0,
has_4_of_a_kind_case = 0,
has_full_house_case = 0;
while (i++ < TEST_SIZE){
card deck[DECK_SIZE];
init_deck(deck);
shuffle_deck(deck);
// deck is uniformly randomized, draw the first 7
no_pair_case += has_pairs(7, deck, 0);
one_pair_case += has_pairs(7, deck, 1);
two_pairs_case += has_pairs(7, deck, 2);
has_3_of_a_kind_case += has_x_of_a_kind(7, deck, 3);
has_4_of_a_kind_case += has_x_of_a_kind(7, deck, 4);
has_full_house_case += has_full_house(7, deck);
}
printf("Probablity of no pair in a 7 cards hand: %lf %%: \n", (100.0 * no_pair_case) / TEST_SIZE);
printf("Probablity of one pair in a 7 cards hand: %lf %%: \n", (100.0 * one_pair_case) / TEST_SIZE);
printf("Probablity of two pairs in a 7 cards hand: %lf %%: \n", (100.0 * two_pairs_case) / TEST_SIZE);
printf("Probablity of 3 of a kind in a 7 cards hand: %lf %%: \n", (100.0 * has_3_of_a_kind_case) / TEST_SIZE);
printf("Probablity of full house in a 7 cards hand: %lf %%: \n", (100.0 * has_full_house_case) / TEST_SIZE);
printf("Probablity of 4 of a kind in a 7 cards hand: %lf %%: \n", (100.0 * has_4_of_a_kind_case) / TEST_SIZE);
return 0;
}
void init_deck(card deck[]){
int k = 0;
for (int i = 1; i <= 13; i ++){
for (int j = DIAMONDS; j <= SPADES; j ++){
card c = { i , j };
deck[k++] = c;
}
}
}
void shuffle_deck(card deck[]){
// uniformly randomize the card deck sequence
for (int i = 0; i < DECK_SIZE; i ++){
int rand_index = rand() % (DECK_SIZE - i) + i; // [i, 51]
// swap
card temp = { deck[i].pip, deck[i].s };
deck[i].pip = deck[rand_index].pip;
deck[i].s = deck[rand_index].s;
deck[rand_index].pip = temp.pip;
deck[rand_index].s = temp.s;
}
}
void print_deck(card deck[]){
for (int i = 0; i < DECK_SIZE; i ++){
printf("%d-%d, ", deck[i].pip, deck[i].s);
}
}
int has_pairs(int n, card hand[], int pair){
// bucket count
int dict[14] = {0};
for (int i = 0; i < n; i++){
int pip = hand[i].pip;
dict[pip]++;
}
int pairs_count = 0;
for (int i = 1; i <= 13; i++){
if (dict[i] == 2) {
pairs_count++;
}
}
return pairs_count == pair;
}
int has_x_of_a_kind(int n, card hand[], int x) {
// bucket count
int dict[14] = {0};
for (int i = 0; i < n; i++){
int pip = hand[i].pip;
dict[pip]++;
}
for (int i = 1; i <= 13; i++){
if (dict[i] == x) {
return 1;
}
}
return 0;
}
int has_full_house(int n, card hand[]) {
// bucket count
int dict[14] = {0};
for (int i = 0; i < n; i++){
int pip = hand[i].pip;
dict[pip]++;
}
int three_of_a_kind_pip = 0;
int pair_pip = 0;
for (int i = 1; i <= 13; i++){
if (dict[i] >= 3) {
three_of_a_kind_pip = i;
}
if (dict[i] >= 2 && i != three_of_a_kind_pip) {
pair_pip = i;
}
}
return pair_pip && three_of_a_kind_pip && pair_pip != three_of_a_kind_pip;
}
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