From 9ee5e675145379cf11ca8545649e534bf6834941 Mon Sep 17 00:00:00 2001
From: Ren Baoshuo <i@baoshuo.ren>
Date: Wed, 21 Oct 2020 21:27:03 +0800
Subject: [PATCH] P3131 [USACO16JAN] Subsequences Summing to Sevens S

R40246968
---
 problem/P3131/P3131.cpp | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 problem/P3131/P3131.cpp

diff --git a/problem/P3131/P3131.cpp b/problem/P3131/P3131.cpp
new file mode 100644
index 00000000..bc5495b1
--- /dev/null
+++ b/problem/P3131/P3131.cpp
@@ -0,0 +1,24 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+long long a[50005];
+
+int main() {
+    int n, k;
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> k;
+        a[i] = a[i - 1] + k;
+    }
+    for (int i = n; i > 0; i--) {
+        for (int j = 1; j + i <= n; j++) {
+            if ((a[i + j] - a[j]) % 7 == 0) {
+                cout << i << endl;
+                return 0;
+            }
+        }
+    }
+    cout << 0 << endl;
+    return 0;
+}