From 8ae888d746d5a8f17bac799b66f97fd47ea0ded4 Mon Sep 17 00:00:00 2001
From: Gwangseok Han <66068653+c0natus@users.noreply.github.com>
Date: Wed, 11 Dec 2024 13:50:23 +0900
Subject: [PATCH 1/2] Create 10986 gwangseok.py

---
 BaekJoon/10986/gwangseok.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 BaekJoon/10986/gwangseok.py

diff --git a/BaekJoon/10986/gwangseok.py b/BaekJoon/10986/gwangseok.py
new file mode 100644
index 0000000..7ce6b95
--- /dev/null
+++ b/BaekJoon/10986/gwangseok.py
@@ -0,0 +1,20 @@
+from collections import defaultdict
+
+N, M = map(int, input().split())
+nums = list(map(int, input().split()))
+
+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)

From 151f36867054f55b7c9be3bd0effdea8b9b0f65e Mon Sep 17 00:00:00 2001
From: Gwangseok Han <66068653+c0natus@users.noreply.github.com>
Date: Tue, 17 Dec 2024 13:36:08 +0900
Subject: [PATCH 2/2] Update 10986 gwangseok.py

---
 BaekJoon/10986/gwangseok.py | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/BaekJoon/10986/gwangseok.py b/BaekJoon/10986/gwangseok.py
index 7ce6b95..32f7046 100644
--- a/BaekJoon/10986/gwangseok.py
+++ b/BaekJoon/10986/gwangseok.py
@@ -3,18 +3,33 @@
 N, M = map(int, input().split())
 nums = list(map(int, input().split()))
 
-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)
+# <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)
-    k = len(values)
-    ans += (k-1) * k // 2 # 0 + ... + k-1
-    if key == 0: # 본인 포함
-        ans += k
+    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)