From 45b55c05af59abe10b7df6a43564c458ca6c7ad1 Mon Sep 17 00:00:00 2001
From: Evan Burkey <evan@burkey.co>
Date: Tue, 21 Dec 2021 07:48:19 -0800
Subject: [PATCH] 2015-06

---
 src/2015/06.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 109 insertions(+), 3 deletions(-)

diff --git a/src/2015/06.c b/src/2015/06.c
index 56f4b7a..2207174 100644
--- a/src/2015/06.c
+++ b/src/2015/06.c
@@ -1,12 +1,118 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+
+#ifdef __linux__
+#include <bsd/stdlib.h>
+#endif
 
 #include "lfinput.h"
+#include "lfmath.h"
 
 #define GRID_SZ 1000
 
-void advent2015day06(void) {
+typedef struct {
+    int mode; /* 0 = on, 1 = off, 2 = toggle */
+    int x0;
+    int y0;
+    int x1;
+    int y1;
+} s1503;
 
-    char *input = get_lines("input/2015/06");
-    free(input);
+static void get_coords(char *s, int *x, int *y) {
+    char buf[8];
+    char *c = s;
+    int i = 0;
+    const char *errstr = NULL;
+
+    while (*c != ',') {
+        buf[i++] = *c;
+        ++c;
+    }
+    buf[i] = '\0';
+    *x = (int)strtonum(buf, 0, 999, &errstr);
+    if (NULL != errstr) {
+        exit(1);
+    }
+
+    memset(buf, 0, sizeof(char) * 8);
+    i = 0;
+    ++c;
+    while (*c != '\0') {
+        buf[i++] = *c;
+        ++c;
+    }
+    buf[i] = '\0';
+    *y = (int)strtonum(buf, 0, 999, &errstr);
+    if (NULL != errstr) {
+        exit(1);
+    }
+}
+
+static int run(s1503 *ins, size_t sz, int p1) {
+    int grid[GRID_SZ][GRID_SZ];
+    memset(grid, 0, sizeof(int) * GRID_SZ * GRID_SZ);
+
+    for (size_t i = 0; i < sz; ++i) {
+        for (int x = ins[i].x0; x <= ins[i].x1; ++x) {
+            for (int y = ins[i].y0; y <= ins[i].y1; ++y) {
+                switch (ins[i].mode) {
+                case 0: /* on */
+                    if (p1) { grid[x][y] = 1; }
+                    else {grid[x][y] += 1; }
+                    break;
+
+                case 1: /* off */
+                    if (p1) { grid[x][y] = 0; }
+                    else {grid[x][y] = max_int(0, grid[x][y] - 1); }
+                    break;
+
+                case 2: /* toggle */
+                    if (p1) { grid[x][y] = grid[x][y] == 1 ? 0 : 1; }
+                    else {grid[x][y] += 2; }
+                    break;
+                }
+            }
+        }
+    }
+
+    int c = 0;
+    for (int x = 0; x < GRID_SZ; ++x) {
+        for (int y = 0; y < GRID_SZ; ++y) {
+            c += grid[x][y];
+        }
+    }
+    return c;
+}
+
+void advent2015day06(void) {
+    size_t sz = 0;
+    char **input = get_lines("input/2015/06", &sz);
+    s1503 ins[sz];
+    for (size_t i = 0; i < sz; ++i) {
+        char *s = malloc(sizeof(char) * 64);
+        strcpy(s, input[i]);
+        size_t sp_sz = 0;
+        char **sp = split(s, &sp_sz, " ");
+
+        if (sp_sz == 4) {
+            ins[i].mode = 2;
+            get_coords(sp[1], &ins[i].x0, &ins[i].y0);
+            get_coords(sp[3], &ins[i].x1, &ins[i].y1);
+        } else {
+            if (strcmp(sp[1], "on") == 0) {
+                ins[i].mode = 0;
+            } else {
+                ins[i].mode = 1;
+            }
+            get_coords(sp[2], &ins[i].x0, &ins[i].y0);
+            get_coords(sp[4], &ins[i].x1, &ins[i].y1);
+        }
+
+        del_split(sp);
+    }
+    del_lines(input);
+
+    printf("%d\n", run(ins, sz, 1));
+    printf("%d\n", run(ins, sz, 0));
 }