atcoder/abc053D

Author: xirc

atcoder/abc053/D/main.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+int N;
+vector<int> A;
+
+int solve() {
+    unordered_map<int,int> mp;
+    for (auto a : A) {
+        ++mp[a];
+    }
+
+    int ans = N;
+    int m = 0;
+    for (auto e : mp) {
+        auto c = e.second;
+        int r = (c - 1) % 2 + 1;
+        ans -= (c - r);
+        if (r == 2) ++m;
+    }
+    if (m % 2 == 0) {
+        ans -= m;
+    } else {
+        ans -= m + 1;
+    }
+    return ans;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    cin >> N;
+    A.assign(N, 0);
+    for (int i = 0; i < N; ++i) {
+        cin >> A[i];
+    }
+    cout << solve() << endl;
+
+    return 0;
+}