Day13

day13/c/day13.c

@@ -0,0 +1,149 @@
+#include <math.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <omp.h>
+
+#define CHARS_MAX 64
+#define MAX_MACHINES 1024
+#define max(a,b) ((a) > (b) ? (a) : (b))
+#define min(a,b) ((a) < (b) ? (a) : (b))
+
+typedef struct button {
+    uint64_t x;
+    uint64_t y;
+} button_t;
+
+typedef struct machine {
+    button_t button_A;
+    button_t button_B;
+    uint64_t x;
+    uint64_t y;
+} machine_t;
+
+int64_t extended_euclidian(int64_t a, int64_t b, int64_t *x, int64_t *y);
+
+int main() {
+    char *p, *buf, c;
+
+    buf = calloc(CHARS_MAX, sizeof(char));
+    p = buf;
+
+    int step = 0;
+
+    machine_t *machines = calloc(MAX_MACHINES, sizeof(machines[0]));
+    int machine_count = 0;
+
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        if (c != '\n') {
+            continue;
+        }
+
+        switch (step) {
+            case 0:
+                p = buf;
+                while (*p != '+') p++;
+                p++;
+                sscanf(p, "%lu", &machines[machine_count].button_A.x);
+                while (*p != '+') p++;
+                p++;
+                sscanf(p, "%lu", &machines[machine_count].button_A.y);
+                break;
+            case 1:
+                p = buf;
+                while (*p != '+') p++;
+                p++;
+                sscanf(p, "%lu", &machines[machine_count].button_B.x);
+                while (*p != '+') p++;
+                p++;
+                sscanf(p, "%lu", &machines[machine_count].button_B.y);
+                break;
+            case 2:
+                p = buf;
+                while (*p != '=') p++;
+                p++;
+                sscanf(p, "%lu", &machines[machine_count].x);
+                while (*p != '=') p++;
+                p++;
+                sscanf(p, "%lu", &machines[machine_count].y);
+                machine_count++;
+                break;
+            case 3:
+                break;
+        }
+        step++;
+        if (step == 4) {
+            step = 0;
+        }
+        memset(buf, 0, CHARS_MAX);
+        p = buf;
+    }
+
+    free(buf);
+
+    uint64_t tokens = 0;
+#pragma omp parallel for
+    for (int i = 0; i < machine_count; i++) {
+        uint64_t least_tokens = 0;
+        for (int j = 0; j <= 100; j++) {
+            for (int k = 0; k <= 100; k++) {
+                int x = machines[i].button_A.x * j + machines[i].button_B.x * k;
+                int y = machines[i].button_A.y * j + machines[i].button_B.y * k;
+                if (x == machines[i].x && y == machines[i].y) {
+                    uint64_t current_tokens = 3 * j + k;
+                    if (least_tokens == 0 || least_tokens > current_tokens) {
+                        least_tokens = current_tokens;
+                    }
+                }
+            }
+        }
+#pragma omp critical
+        {
+            tokens += least_tokens;
+        }
+    }
+    printf("%lu\n", tokens);
+
+    double ttokens = 0.0;
+    for (int i = 0; i < machine_count; i++) {
+        machines[i].x += 10000000000000;
+        machines[i].y += 10000000000000;
+        //printf("%i %lu %lu %lu %lu %lu %lu\n", i, machines[i].x, machines[i].y, machines[i].button_A.x, machines[i].button_A.y, machines[i].button_B.x, machines[i].button_B.y);
+        int64_t x, y;
+        double a = (double)machines[i].button_A.x - (double)machines[i].button_A.y;
+        double b = (int64_t)machines[i].button_B.x - (double)machines[i].button_B.y;
+        double c = (double)machines[i].x - (double)machines[i].y;
+        double k2 = ((double)machines[i].x - (double)machines[i].button_A.x * c / a) / ((double)machines[i].button_B.x - (double)machines[i].button_A.x * b / a);
+        double k1 = (c - b * k2) / a;
+        double tmp;
+        double r1 = modf(k1, &tmp);
+        double r2 = modf(k2, &tmp);
+
+        if ((r1 < 0.001 || r1 > 0.999) && (r2 < 0.001 || r2 > 0.999)) {
+            ttokens += k1 * 3.0 + k2;
+        }
+    }
+    printf("%0.0f\n", ttokens);
+
+
+    free(machines);
+
+}
+
+int64_t extended_euclidian(int64_t a, int64_t b, int64_t *x, int64_t *y) {
+    if (a == 0) {
+        *x = 0;
+        *y = 1;
+        return b;
+    }
+
+    int64_t x1, y1;
+    int64_t gcd = extended_euclidian(b % a, a, &x1, &y1);
+
+    *x = y1 - (b / a) * x1;
+    *y = x1;
+
+    return gcd;
+}

day13/sample.txt

@@ -0,0 +1,15 @@
+Button A: X+94, Y+34
+Button B: X+22, Y+67
+Prize: X=8400, Y=5400
+
+Button A: X+26, Y+66
+Button B: X+67, Y+21
+Prize: X=12748, Y=12176
+
+Button A: X+17, Y+86
+Button B: X+84, Y+37
+Prize: X=7870, Y=6450
+
+Button A: X+69, Y+23
+Button B: X+27, Y+71
+Prize: X=18641, Y=10279