adventofcode2022/day19/robot.c

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

#define BUFFER_SIZE 256
#define MAX_BLUEPRINT 128
#define MAX_TIME 24
#define PART_TWO_NUM 3
#define PART_TWO_TIME 32

#define max(a,b) (a >= b ? a : b)

typedef struct blueprint {
    int ore_cost;
    int clay_cost;
    int obsidian_cost[2];
    int geode_cost[2];
} BLUEPRINT;

int bestGeode(BLUEPRINT, int[], int[], int, int);

int bestMax = 0;

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

    while ((c = getchar()) != EOF) {
        *p++ = c;
        if (c == '\n') {
            sscanf(buf, "Blueprint %*i: Each ore robot costs %i ore. Each clay robot costs %i ore. Each obsidian robot costs %i ore and %i clay. Each geode robot costs %i ore and %i obsidian.", &blueprints[blueprint_count].ore_cost, &blueprints[blueprint_count].clay_cost, &blueprints[blueprint_count].obsidian_cost[0], &blueprints[blueprint_count].obsidian_cost[1], &blueprints[blueprint_count].geode_cost[0], &blueprints[blueprint_count].geode_cost[1]);
            blueprint_count++;
            memset(buf, 0, BUFFER_SIZE);
            p = buf;
        }
    }

    int *quality_levels = (int*)malloc(blueprint_count * sizeof(int));
    memset(quality_levels, 0, blueprint_count * sizeof(int));
    // Check each blueprint
    for (int i = 0; i < blueprint_count; i++) {
        bestMax = 0;
        int stash[4] = {0,0,0,0};
        int robots[4] = {1,0,0,0};


        quality_levels[i] = bestGeode(blueprints[i], stash, robots, 0, MAX_TIME);
    }

    int sum = 0;
    for (int i = 0; i < blueprint_count; i++) {
        sum += (i+1) * quality_levels[i];
    }
    
    printf("%i\n", sum);
    free(quality_levels);


    unsigned product = 1;
    for (int i = 0; i < PART_TWO_NUM; i++) {
        bestMax = 0;
        int stash[4] = {0,0,0,0};
        int robots[4] = {1,0,0,0};

        product *= bestGeode(blueprints[i], stash, robots, 0, PART_TWO_TIME);
    }
    printf("%u\n", product);
}

int bestGeode(BLUEPRINT blueprint, int stash[], int robots[], int sum, int time) {
    if (time <= 0) {
        return sum;
    }

    int pompom = 0;
    for (int i = 1; i <= time; i+=2) {
        pompom += i;
    }
    if (bestMax > sum + pompom) {
        return sum;
    }

    int max = sum;
    int stashCopy[4];
    memcpy(stashCopy, stash, 4*sizeof(int));
    int robotsCopy[4];
    memcpy(robotsCopy, robots, 4*sizeof(int));

    // At every step we decide what robot will we build next (if we can)
    int mostGeodes = 0;

    // Ore robot
    int timeCost = 0, timeCost2 = 0;
    while (stash[0] + timeCost*robots[0] < blueprint.ore_cost) {
        timeCost++;
    }
    // Build time
    timeCost++;
    // We don't have the time left to build this
    if (time - timeCost >= 0) {
        for (int j = 0; j < 4; j++) {
            stash[j] = stash[j] + timeCost * robots[j];
        }
        stash[0] -= blueprint.ore_cost;
        robots[0]++;
        mostGeodes = bestGeode(blueprint, stash, robots, sum, time - timeCost);
        memcpy(stash, stashCopy, 4*sizeof(int));
        memcpy(robots, robotsCopy, 4*sizeof(int));

        if (mostGeodes > max) {
            max = mostGeodes;
        }
    }

    // Clay robot
    timeCost = 0;
    while (stash[0] + timeCost*robots[0] < blueprint.clay_cost) {
        timeCost++;
    }
    // Build time
    timeCost++;
    // We don't have the time left to build this
    if (time - timeCost >= 0) {
        for (int j = 0; j < 4; j++) {
            stash[j] = stash[j] + timeCost * robots[j];
        }
        stash[0] -= blueprint.clay_cost;
        robots[1]++;
        mostGeodes = bestGeode(blueprint, stash, robots, sum, time - timeCost);
        memcpy(stash, stashCopy, 4*sizeof(int));
        memcpy(robots, robotsCopy, 4*sizeof(int));
        if (mostGeodes > max) {
            max = mostGeodes;
        }
    }

    // Obsidian robot
    // Only if we have at least 1 clay robot
    if (robots[1] > 0) {
        timeCost = timeCost2 = 0;
        while (stash[0] + timeCost*robots[0] < blueprint.obsidian_cost[0]) {
            timeCost++;
        }
        while (stash[1] + timeCost2*robots[1] < blueprint.obsidian_cost[1]) {
            timeCost2++;
        }

        timeCost = max(timeCost, timeCost2);
        // build time
        timeCost++;
        if (time - timeCost >= 0) {
            for (int j = 0; j < 4; j++) {
                stash[j] = stash[j] + timeCost * robots[j];
            }
            stash[0] -= blueprint.obsidian_cost[0];
            stash[1] -= blueprint.obsidian_cost[1];
            robots[2]++;
            mostGeodes = bestGeode(blueprint, stash, robots, sum, time - timeCost);
            memcpy(stash, stashCopy, 4*sizeof(int));
            memcpy(robots, robotsCopy, 4*sizeof(int));
            if (mostGeodes > max) {
                max = mostGeodes;
            }
        }
    }

    // Geode robot
    // Only if we have at least 1 obsidian robot
    if (robots[2] > 0) {
        timeCost = timeCost2 = 0;
        while (stash[0] + timeCost*robots[0] < blueprint.geode_cost[0]) {
            timeCost++;
        }
        while (stash[2] + timeCost2*robots[2] < blueprint.geode_cost[1]) {
            timeCost2++;
        }

        timeCost = max(timeCost, timeCost2);
        // build time
        timeCost++;
        if (time - timeCost >= 0) {
            for (int j = 0; j < 4; j++) {
                stash[j] = stash[j] + timeCost * robots[j];
            }
            stash[0] -= blueprint.geode_cost[0];
            stash[2] -= blueprint.geode_cost[1];
            robots[3]++;
            mostGeodes = bestGeode(blueprint, stash, robots, sum + (time - timeCost), time - timeCost);
            memcpy(stash, stashCopy, 4*sizeof(int));
            memcpy(robots, robotsCopy, 4*sizeof(int));
            if (mostGeodes > max) {
                max = mostGeodes;
            }
        }
    }

    if (max > bestMax) {
        bestMax = max;
    }

    return max;
}