atcoder/abc044C

Author: xirc

atcoder/abc044/C/main.cpp

@@ -0,0 +1,40 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = int64_t;
+using ff = long double;
+
+int N, A;
+vector<int> xs;
+
+ll solve() {
+    const int M = 50 * 50;
+    vector<vector<ll>> DP(N+1, vector<ll>(M+1, 0));
+    DP[0][0] = 1;
+
+    for (auto x : xs) {
+        for (int i = N; i > 0; --i) {
+            for (int j = M; j - x >= 0; --j) {
+                DP[i][j] += DP[i-1][j-x];
+            }
+        }
+    }
+
+    ll ans = 0;
+    for (int i = 1; i <= N; ++i) {
+        ans += DP[i][i*A];
+    }
+    return ans;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> N >> A;
+    xs.assign(N, 0);
+    for (auto &x : xs) cin >> x;
+    cout << solve() << endl;
+
+    return 0;
+}