1 files changed, 22 insertions, 0 deletions
diff --git a/19/day1/palindrometer.cpp b/19/day1/palindrometer.cpp
new file mode 100644
index 0000000..65914fa
--- /dev/null
+++ b/19/day1/palindrometer.cpp
@@ -0,0 +1,22 @@
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+
+int P[2][100001];
+
+int main() {
+	string S; cin >> S;
+	int N = S.size();
+	for (int i = 0; i < 2; ++i) {
+		for (int j = 0, l = 0, r = 0; j < N; ++j) {
+			int k = (j > r ? !i : min(P[i][l + r - j + i], r - j + 1));
+			while (j - k - i >= 0 && j + k < N && S[j - k - i] == S[j + k]) ++k;
+			P[i][j] = k--;
+			if (j + k > r) l = j - k - i, r = j + k;
+		}
+	}
+
+	ll ans = 0;
+	for (int i = 0; i < N; ++i) ans += P[0][i] + P[1][i];
+	cout << ans << '\n';
+}
+\ No newline at end of file