From f71713079959f0541a025e292bfc8bd240e7bbae Mon Sep 17 00:00:00 2001
From: Peter <peterr.00000@gmail.com>
Date: Wed, 1 Dec 2021 23:53:22 +0800
Subject: [PATCH] Day 1 solutions

---
 .gitignore |  7 ++++++
 1/1-1.c    | 21 ++++++++++++++++++
 1/1-2.c    | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 1/1-1.c
 create mode 100644 1/1-2.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1518e5d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+*
+!/**/
+!*.*
+
+*.out
+*.swp
+.vscode/
diff --git a/1/1-1.c b/1/1-1.c
new file mode 100644
index 0000000..6ebb892
--- /dev/null
+++ b/1/1-1.c
@@ -0,0 +1,21 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+
+int main(int argc, char const *argv[])
+{
+    FILE *p_file = fopen("input", "r");
+    char line[50];
+    uint increases = 0;
+    uint previous_depth = 0;
+    while (fgets(line, sizeof line, p_file) != NULL)
+    {
+        if (atoi(line) > previous_depth)
+        {
+            increases++;
+        }
+        previous_depth = atoi(line);
+    }
+    printf("%u\n", increases - 1);
+    return 0;
+}
diff --git a/1/1-2.c b/1/1-2.c
new file mode 100644
index 0000000..4a0bc64
--- /dev/null
+++ b/1/1-2.c
@@ -0,0 +1,64 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+#include <stdbool.h>
+
+#define N_WINDOWS 4
+#define WINDOW_LENGTH 3
+
+typedef struct
+{
+    uint sum;
+    uint count;
+    bool written; // IGNORE COMPARISONS AT THE START.
+} MEASUREMENT_WINDOW;
+
+int main(int argc, char const *argv[])
+{
+    FILE *p_file = fopen("input", "r");
+    char line[50];
+    uint increases = 0;
+
+    MEASUREMENT_WINDOW windows[N_WINDOWS];
+
+    uint i = 0;
+    while (fgets(line, sizeof line, p_file) != NULL)
+    {
+        uint n = atoi(line);
+        // UPDATE MEASURING WINDOWS
+        for (size_t j = 0; j < N_WINDOWS; j++)
+        {
+            MEASUREMENT_WINDOW *window = &windows[j];
+            if ((i - j) % N_WINDOWS == 0)
+            {
+                window->count = 0;
+                window->sum = 0;
+                window->written = true;
+            }
+            if (window->written && window->count < 3)
+            {
+                window->sum += n;
+                window->count++;
+            }
+        }
+        // COMPARE WINDOWS
+        for (size_t j = 0; j < N_WINDOWS; j++)
+        {
+            MEASUREMENT_WINDOW *window = &windows[j];
+            // ONE WINDOW IS READY TO BE COMPARED
+            if (window->count == 3)
+            {
+                window->count++; // PREVENT DOUBLE-COMPARE OF WINDOW.
+                MEASUREMENT_WINDOW last_window = windows[(j + N_WINDOWS - 1) % 4];
+                if (last_window.written && window->written && window->sum > last_window.sum)
+                {
+                    increases++;
+                }
+                continue;
+            }
+        }
+        i++;
+    }
+    printf("%u\n", increases);
+    return 0;
+}