[Week13] BOJ 2143: 두 배열의 합

Author: Hexeong

weekly/week13/BOJ_2143_두배열의합/Hexeong.java

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+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.HashMap;
+import java.util.List;
+import java.util.StringTokenizer;
+import java.util.stream.Collectors;
+
+public class Main {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        int T = Integer.parseInt(br.readLine());
+        int A_n = Integer.parseInt(br.readLine());
+        st = new StringTokenizer(br.readLine());
+        int[] A = new int[A_n];
+        for (int i = 0; i < A_n; i++) {
+            A[i] = Integer.parseInt(st.nextToken());
+        }
+
+        int B_n = Integer.parseInt(br.readLine());
+        st = new StringTokenizer(br.readLine());
+        int[] B = new int[B_n];
+        for (int i = 0; i < B_n; i++) {
+            B[i] = Integer.parseInt(st.nextToken());
+        }
+
+        HashMap<Integer, Integer> A_map = new HashMap<>();
+        HashMap<Integer, Integer> B_map = new HashMap<>();
+
+        for (int k = 1; k <= A_n; k++) {
+            for (int i = 0; i <= A_n - k; i++) {
+                int sum = 0;
+                for (int j = 0; j < k; j++) {
+                    sum += A[i + j];
+                }
+                if (A_map.containsKey(sum)) {
+                    A_map.put(sum, A_map.get(sum) + 1);
+                } else  {
+                    A_map.put(sum, 1);
+                }
+            }
+        }
+
+        for (int k = 1; k <= B_n; k++) {
+            for (int i = 0; i <= B_n - k; i++) {
+                int sum = 0;
+                for (int j = 0; j < k; j++) {
+                    sum += B[i + j];
+                }
+                if (B_map.containsKey(sum)) {
+                    B_map.put(sum, B_map.get(sum) + 1);
+                } else  {
+                    B_map.put(sum, 1);
+                }
+            }
+        }
+
+        long output = 0;
+        List<Integer> list = A_map.keySet().stream().sorted().collect(Collectors.toList());
+        for (int a_key : list) {
+            long a_cnt = A_map.get(a_key);
+
+            if (!B_map.containsKey(T - a_key)) continue;
+
+            long b_cnt = B_map.get(T - a_key);
+            output += a_cnt * b_cnt;
+        }
+
+        System.out.println(output);
+    }
+}