백준 10986번 나머지 합 java solution

mong3125/수학/BOJ10986.java

@@ -0,0 +1,31 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.StringTokenizer;
+
+public class BOJ10986 {
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        int N = Integer.parseInt(st.nextToken());
+        int M = Integer.parseInt(st.nextToken());
+
+        st = new StringTokenizer(br.readLine());
+        int[] remainders = new int[N + 1];  // 부분 합을 M으로 나눈 리스트
+        int[] remainders_count = new int[M];     // 나머지 개수
+        for (int i = 1; i <= N; i++) {
+            remainders[i] = (remainders[i - 1] + Integer.parseInt(st.nextToken())) % M;
+            remainders_count[remainders[i]] += 1;
+        }
+
+        long count = 0;
+        for (int i = 0; i < M; i++) {
+            count += (long) remainders_count[i] * (remainders_count[i] - 1) / 2;   // 조합
+        }
+
+        count += remainders_count[0];  // 나머지가 0일때 (i = j 일때)
+
+        System.out.println(count);
+    }
+}