From df6b6dd888b8469a4228cea249aba7c369c6cc23 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Tue, 1 Dec 2020 21:31:03 -0600
Subject: [PATCH] feat: decrease complexity of 2020-12-01 p1 & p2

---
 day_1/main.cpp | 76 ++++++++++++++++++++++++++++----------------------
 1 file changed, 43 insertions(+), 33 deletions(-)

diff --git a/day_1/main.cpp b/day_1/main.cpp
index 3c98604..d70b3fb 100644
--- a/day_1/main.cpp
+++ b/day_1/main.cpp
@@ -1,6 +1,7 @@
 #include <iostream>
 #include <fstream>
 #include <vector>
+#include <unordered_map>
 
 int part_1();
 int part_2();
@@ -11,19 +12,53 @@ int main() {
 }
 
 int part_1() {
-    std::vector<int> vector;
+    std::unordered_map<int, int> map;
     std::ifstream input("../input.txt");
     std::string line;
 
-    while(std::getline(input, line)) {
-        int num = std::stoi(line);
-        vector.push_back(num);
+    int i = 0;
+    while (std::getline(input, line)) {
+        std::pair<int, int> pair {std::stoi(line), i};
+        map.insert(pair);
+        i++;
     }
 
-    for (int i : vector) {
-        for (int j : vector) {
-            if (i + j == 2020) {
-                std::cout << (i * j) << std::endl;
+    for (std::pair<int, int> pair : map) {
+        int num = pair.first;
+        int compliment = 2020 - num;
+         if (map.contains(compliment)) {
+             std::cout << (num * compliment) << std::endl;
+             return 0;
+         }
+    }
+
+    return 1;
+}
+
+
+int part_2() {
+    std::unordered_map<int, int> map;
+    std::ifstream input("../input.txt");
+    std::string line;
+
+    int i = 0;
+    while (std::getline(input, line)) {
+        std::pair<int, int> pair {std::stoi(line), i};
+        map.insert(pair);
+        i++;
+    }
+
+    for (std::pair<int, int> first_pair : map) {
+        int num = first_pair.first;
+        int compliment = 2020 - num;
+
+        // Still two other numbers we gotta find from here
+        for (std::pair<int, int> second_pair : map) {
+            int second_num = second_pair.first;
+            int second_compliment = compliment - second_num;
+
+            if (map.contains(second_compliment)) {
+                std::cout << (num * second_num * second_compliment) << std::endl;
                 return 0;
             }
         }
@@ -32,28 +67,3 @@ int part_1() {
     return 1;
 }
 
-
-int part_2() {
-    std::vector<int> vector;
-    std::ifstream input("../input.txt");
-    std::string line;
-
-    while(std::getline(input, line)) {
-        int num = std::stoi(line);
-        vector.push_back(num);
-    }
-
-    for (int i : vector) {
-        for (int j : vector) {
-            for (int k : vector) {
-                if (i + j + k == 2020) {
-                    std::cout << (i * j * k) << std::endl;
-                    return 0;
-                }
-            }
-        }
-    }
-
-    return 1;
-}
-