diff --git a/과제2폴더/2-1.png b/과제2폴더/2-1.png
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diff --git a/과제2폴더/2-1.txt b/과제2폴더/2-1.txt
new file mode 100644
index 0000000..fc4bac0
--- /dev/null
+++ b/과제2폴더/2-1.txt
@@ -0,0 +1,14 @@
+#include <string>
+#include <vector>
+
+using namespace std;
+
+int solution(int n, int k) {
+    int answer = 0;
+    
+    // 총액
+    answer = n * 12000;
+    answer += (k - (n / 10)) * 2000;
+    
+    return answer;
+}
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diff --git a/과제2폴더/2-2.png b/과제2폴더/2-2.png
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diff --git a/과제2폴더/2-2.txt b/과제2폴더/2-2.txt
new file mode 100644
index 0000000..b3bab49
--- /dev/null
+++ b/과제2폴더/2-2.txt
@@ -0,0 +1,21 @@
+#include <string>
+#include <vector>
+
+using namespace std;
+
+int solution(vector<vector<int>> board, int k) {
+    int answer = 0;
+    
+    for (int i=0; i<board.size(); i++)
+    {
+        for (int j=0; j<board[i].size(); j++)
+        {
+            if (i+j <= k)
+            {
+                answer += board[i][j];
+            }
+        }   
+    }
+    
+    return answer;
+}
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diff --git a/과제2폴더/2-3.png b/과제2폴더/2-3.png
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diff --git a/과제2폴더/2-3.txt b/과제2폴더/2-3.txt
new file mode 100644
index 0000000..f541389
--- /dev/null
+++ b/과제2폴더/2-3.txt
@@ -0,0 +1,91 @@
+#include <string>
+#include <vector>
+#include <map>
+#include <cmath>
+#include <algorithm>
+
+using namespace std;
+
+static bool comp(pair<int, int>& a, pair<int, int>& b){
+	return a.second > b.second;
+}
+
+int solution(int a, int b, int c, int d) {
+    int answer = 0;
+    map<int,int> m;
+    m[a]++;
+    m[b]++;
+    m[c]++;
+    m[d]++;
+    
+    vector<pair<int, int>> v(m.begin(), m.end());
+	sort(v.begin(), v.end(), comp);
+    
+    bool n3 = false;
+    bool n2 = false;
+    bool n1 = false;
+    bool n0 = false;
+        
+    for (auto it = v.begin(); it != v.end(); ++it) {        
+        switch(it->second)
+        {
+            // 4개 같음
+            case 4:
+                answer = 1111 * it->first;
+                break;
+            // 3개 같음
+            case 3:
+                answer = 10 * it->first;
+                n3 = true;
+                break;
+            // 2개 같음
+            case 2:
+                // 2개 이후 2개
+                if (n2) 
+                {
+                    answer = (answer + it->first) * abs(answer - it->first);
+                    break;
+                }
+                
+                answer = it->first;
+                n2 = true;                
+                break;
+            // 1개 같음
+            case 1:
+                // 3개 이후 1개
+                if (n3)
+                {
+                    answer = (answer + it->first) * (answer + it->first);
+                    break;
+                }
+                
+                // 2개 이후 1개
+                if (n2)
+                {
+                    // 2개 이후 1개 이후 1개
+                    if (n1)
+                    {
+                        answer = answer * - it->first;
+                        break;
+                    }
+                    
+                    answer = - it->first;
+                    n1 = true;
+                    break;
+                }
+                
+                // 1개 이후 1개                
+                if (n1)
+                {                    
+                    answer < it->first ? answer : it->first;
+                    break;
+                }
+                
+                answer = it->first;                
+                n1 = true;
+                break;
+        }
+    }
+    
+    return answer;
+}
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diff --git a/과제2폴더/2-4.png b/과제2폴더/2-4.png
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diff --git a/과제2폴더/2-4.txt b/과제2폴더/2-4.txt
new file mode 100644
index 0000000..0edb85e
--- /dev/null
+++ b/과제2폴더/2-4.txt
@@ -0,0 +1,35 @@
+#include <string>
+#include <vector>
+
+using namespace std;
+
+int solution(vector<vector<int>> dots) {
+    int answer = 0;
+    
+    // 뭐여 실수만 되네?
+    double dx = dots[0][0] - dots[1][0];
+    double dy = dots[0][1] - dots[1][1];
+    double dx2 = dots[2][0] - dots[3][0];
+    double dy2 = dots[2][1] - dots[3][1];
+    
+    if (dx/dy == dx2/dy2)
+        return 1;
+    
+    dx = dots[0][0] - dots[2][0];
+    dy = dots[0][1] - dots[2][1];
+    dx2 = dots[1][0] - dots[3][0];
+    dy2 = dots[1][1] - dots[3][1];
+    
+    if (dx/dy == dx2/dy2)
+        return 1;
+    
+    dx = dots[0][0] - dots[3][0];
+    dy = dots[0][1] - dots[3][1];
+    dx2 = dots[1][0] - dots[2][0];
+    dy2 = dots[1][1] - dots[2][1];
+    
+    if (dx/dy == dx2/dy2)
+        return 1;
+    
+    return answer;
+}
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