adventofcode2022/day11/monkeys.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BUFFER_SIZE 64
#define MONKEY_MAX_STASH 100
#define substitute(w, o) (o == 0 ? w : o)

enum stage {
    INIT,
    ITEM_COUNT,
    ITEMS,
    OPERATION,
    TEST,
    THROW_TRUE,
    THROW_FALSE
};

typedef struct monkey {
    unsigned long stash[MONKEY_MAX_STASH];
    unsigned long stash_size;
    int test;
    int throw_true;
    int throw_false;
    int operation[3];
    unsigned long throw_count;
} MONKEY;

unsigned long operate(unsigned long, int*);

int main() {
    char buf[BUFFER_SIZE], *p, c;
    memset(buf, 0, BUFFER_SIZE);
    p = buf;

    enum stage currentStage = INIT;

    MONKEY *monkeys, *currentMonkey;
    int monkeyCount, itemRemaining;

    while ((c = getchar()) != EOF) {
        *p++ = c;
        if (c == '\n') {
            switch (currentStage) {
                case INIT:
                    sscanf(buf, "%i", &monkeyCount);
                    monkeys = (MONKEY*)malloc(monkeyCount*sizeof(MONKEY));
                    memset(monkeys, 0, monkeyCount*sizeof(MONKEY));
                    currentMonkey = monkeys;
                    currentStage = ITEM_COUNT;
                    break;
                case ITEM_COUNT:
                    sscanf(buf, "%i", &itemRemaining);
                    currentStage = ITEMS;
                    break;
                case ITEMS:
                    sscanf(buf, "%lu", &currentMonkey->stash[currentMonkey->stash_size]);
                    currentMonkey->stash_size++;
                    itemRemaining--;
                    if (itemRemaining == 0) {
                        currentStage = OPERATION;
                    }
                    break;
                case OPERATION:
                    sscanf(buf, "%i %i %i", &currentMonkey->operation[0], &currentMonkey->operation[1], &currentMonkey->operation[2]);
                    currentStage = TEST;
                    break;
                case TEST:
                    sscanf(buf, "%i", &currentMonkey->test);
                    currentStage = THROW_TRUE;
                    break;
                case THROW_TRUE:
                    sscanf(buf, "%i", &currentMonkey->throw_true);
                    currentStage = THROW_FALSE;
                    break;
                case THROW_FALSE:
                    sscanf(buf, "%i", &currentMonkey->throw_false);
                    currentMonkey++;
                    currentStage = ITEM_COUNT;
                    break;
            }

            memset(buf, 0, BUFFER_SIZE);
            p = buf;
        }
    }

    unsigned long simplifier = 1;
    for (int j = 0; j < monkeyCount; j++) {
        simplifier *= monkeys[j].test;
    }

    unsigned long worry, sumItems;
    // Play 20 rounds with tha monkeys
    for (int i = 0; i < 10000; i++) {
        sumItems = 0;
        // Each monkeys
        for (int j = 0; j < monkeyCount; j++) {
            // Each item
            for (int k = 0; k < monkeys[j].stash_size; k++) {
                monkeys[j].throw_count++;
                worry = monkeys[j].stash[k];
                worry = operate(worry, monkeys[j].operation);
                // Don't you worry child
                // worry /= 3;
                if (worry % monkeys[j].test == 0) {
                    monkeys[monkeys[j].throw_true].stash[monkeys[monkeys[j].throw_true].stash_size] = worry % simplifier;
                    monkeys[monkeys[j].throw_true].stash_size++;
                } else {
                    monkeys[monkeys[j].throw_false].stash[monkeys[monkeys[j].throw_false].stash_size] = worry % simplifier;
                    monkeys[monkeys[j].throw_false].stash_size++;
                }
            }
            monkeys[j].stash_size = 0;
            memset(monkeys[j].stash, 0, MONKEY_MAX_STASH*sizeof(unsigned long));
        }
        // Everything was thrown
    }

    unsigned long max1 = 0, max2 = 0;
    for (int i = 0; i < monkeyCount; i++) {
        if (monkeys[i].throw_count > max1) {
            max2 = max1;
            max1 = monkeys[i].throw_count;
        } else if (monkeys[i].throw_count > max2) {
            max2 = monkeys[i].throw_count;
        }
        printf("Monkey %i throw count: %lu\n", i, monkeys[i].throw_count);
    }

    printf("\nMonkey business: %lu\n", max1 * max2);

    free(monkeys);
}

unsigned long operate(unsigned long worry, int* operation) {
    if (operation[1] == 0) {
        return substitute(worry, operation[0]) + substitute(worry, operation[2]);
    } else if (operation[1] == 1) {
        return substitute(worry, operation[0]) * substitute(worry, operation[2]);
    }

    return -1;
}