From 41d290bd2645865603fe21505d0197c5950249b8 Mon Sep 17 00:00:00 2001
From: Peter <peterr.00000@gmail.com>
Date: Fri, 17 Dec 2021 00:18:53 +0800
Subject: [PATCH] Day 16 solutions

---
 16/16-1and2.c | 193 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 193 insertions(+)
 create mode 100644 16/16-1and2.c

diff --git a/16/16-1and2.c b/16/16-1and2.c
new file mode 100644
index 0000000..e4bb28a
--- /dev/null
+++ b/16/16-1and2.c
@@ -0,0 +1,193 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdbool.h>
+
+// SAMPLE INPUT
+#define INPUT "9C0141080250320F1802104A08"
+
+#define TYPE_LITERAL(t) ((t) == 4)
+
+#define HEADER_LEN 6
+#define BIT_TYPE_LEN 15
+#define PACKET_TYPE_LEN 11
+#define BLOCK_LEN 5
+#define DIGIT_LEN 4
+
+typedef long int INTEGER;
+
+char *BIN_MAP[] = {
+    "0000",
+    "0001",
+    "0010",
+    "0011",
+    "0100",
+    "0101",
+    "0110",
+    "0111",
+    "1000",
+    "1001",
+    "1010",
+    "1011",
+    "1100",
+    "1101",
+    "1110",
+    "1111",
+};
+
+typedef struct
+{
+    int packets;
+    int bits;
+    INTEGER value;
+    int version_total;
+} COUNTER;
+
+char *hex2bin(char *hex)
+{
+    char *bin = calloc(strlen(hex) * DIGIT_LEN, sizeof(char));
+    char *bin_ = bin;
+    for (char *c = hex; *c != '\0'; c++)
+    {
+        if (*c >= '0' && *c <= '9')
+            strcpy(bin_, BIN_MAP[*c - '0']);
+        else
+            strcpy(bin_, BIN_MAP[*c - 'A' + 10]);
+        bin_ += DIGIT_LEN;
+    }
+    return bin;
+}
+
+COUNTER *read_literal(char *bin_literal)
+{
+    COUNTER *ctr = calloc(1, sizeof(COUNTER));
+    char value_buf[BUFSIZ] = {0};
+    bool end_of_block = false;
+    for (int i = 0;; i++)
+    {
+        memcpy(&value_buf[i * DIGIT_LEN], &bin_literal[ctr->bits + 1], DIGIT_LEN);
+        if (bin_literal[ctr->bits] == '0')
+            end_of_block = true;
+        ctr->bits += BLOCK_LEN;
+        if (end_of_block)
+            break;
+    }
+    ctr->value = strtol(value_buf, NULL, 2);
+    return ctr;
+}
+
+COUNTER *read_header(char *bin)
+{
+    COUNTER *ctr = calloc(1, sizeof(COUNTER));
+    ctr->bits = HEADER_LEN;
+    INTEGER values[BUFSIZ] = {0};
+    int value_count = 0;
+    char buf[3];
+    memcpy(buf, &bin[0], 3);
+    int version = strtol(buf, NULL, 2);
+    memcpy(buf, &bin[3], 3);
+    int type = strtol(buf, NULL, 2);
+
+    ctr->version_total += version;
+
+    if (TYPE_LITERAL(type))
+    {
+        COUNTER *ctr_ = read_literal(bin + HEADER_LEN);
+        ctr->bits += ctr_->bits;
+        ctr->value = ctr_->value;
+        ctr->packets++;
+        free(ctr_);
+        return ctr;
+    }
+
+    ctr->packets++;
+
+    // READ PACKETS
+    if (bin[6] == '0') // 15 BIT NUMBER
+    {
+        char value_buf[BIT_TYPE_LEN];
+        ctr->bits += BIT_TYPE_LEN + 1;
+        memcpy(value_buf, &bin[HEADER_LEN + 1], BIT_TYPE_LEN);
+        int max_bits = (int)strtol(value_buf, NULL, 2);
+        // printf("TOTAL_LEN %d %s\n", max_bits, value_buf);
+        bin += HEADER_LEN + BIT_TYPE_LEN + 1;
+        int bits = 0;
+        while (bits < max_bits)
+        {
+            COUNTER *ctr_ = read_header(bin);
+            ctr->bits += ctr_->bits;
+            bin += ctr_->bits;
+            bits += ctr_->bits;
+            ctr->version_total += ctr_->version_total;
+            values[value_count] = ctr_->value;
+            value_count++;
+            free(ctr_);
+        }
+    }
+    else
+    { // 11 BIT NUMBER
+        char value_buf[PACKET_TYPE_LEN];
+        ctr->bits += PACKET_TYPE_LEN + 1;
+        memcpy(value_buf, &bin[HEADER_LEN + 1], PACKET_TYPE_LEN);
+        int max_packets = (int)strtol(value_buf, NULL, 2);
+        // printf("TOTAL_PACKETS %d %s\n", max_packets, value_buf);
+        int count = 0;
+        bin += HEADER_LEN + PACKET_TYPE_LEN + 1;
+        while (count < max_packets)
+        {
+            COUNTER *ctr_ = read_header(bin);
+            ctr->bits += ctr_->bits;
+            bin += ctr_->bits;
+            count += ctr_->packets;
+            ctr->version_total += ctr_->version_total;
+            values[value_count] = ctr_->value;
+            value_count++;
+            free(ctr_);
+        }
+    }
+    switch (type)
+    {
+    case 0: // SUM
+        for (int i = 0; i < value_count; i++)
+            ctr->value += values[i];
+        break;
+    case 1: // PROD
+        ctr->value = values[0];
+        for (int i = 1; i < value_count; i++)
+            ctr->value *= values[i];
+        break;
+    case 2: // MIN
+        ctr->value = values[0];
+        for (int i = 1; i < value_count; i++)
+            if (values[i] < ctr->value)
+                ctr->value = values[i];
+        break;
+    case 3: // MAX
+        ctr->value = values[0];
+        for (int i = 1; i < value_count; i++)
+            if (values[i] > ctr->value)
+                ctr->value = values[i];
+        break;
+    case 5: // GT
+        ctr->value = values[0] > values[1];
+        break;
+    case 6: // LT
+        ctr->value = values[0] < values[1];
+        break;
+    case 7: // EQ
+        ctr->value = values[0] == values[1];
+        break;
+    default:
+        printf("ERROR\n");
+    }
+    return ctr;
+}
+
+int main(int argc, char const *argv[])
+{
+    char hex_string[] = INPUT "\0";
+    char *bin = hex2bin(hex_string);
+    COUNTER *ctr = read_header(bin);
+    printf("VERSION_TOTAL %d VALUE %li\n", ctr->version_total, ctr->value);
+    return 0;
+}