[2024-12-10] gwangseok #369

BaekJoon/10986/gwangseok.py

@@ -0,0 +1,35 @@
+from collections import defaultdict
+
+N, M = map(int, input().split())
+nums = list(map(int, input().split()))
+
+# <풀이2>
+cum_sum = 0
+value_j_dict = defaultdict(int)
+for num in nums: # O(N)
+    cum_sum = (cum_sum + num) % M
+    value_j_dict[cum_sum] += 1
+
+ans = 0
+
+for key, values in value_j_dict.items(): # O(M)
+    ans += (values-1) * values // 2 # 0 + ... + k-1
+    if key == 0:
+        ans += values
+
+# <풀이1>
+# cum_num = [0] * N
+# value_j_dict = defaultdict(list)
+# for idx, num in enumerate(nums): # O(N)
+#     cum_num[idx] = (cum_num[idx-1] + num) % M
+#     value_j_dict[cum_num[idx]].append(idx)
+
+# ans = 0
+
+# for key, values in value_j_dict.items(): # O(M)
+#     k = len(values)
+#     ans += (k-1) * k // 2 # 0 + ... + k-1
+#     if key == 0: # 본인 포함
+#         ans += k
+
+print(ans)