atcoder/abc083D

Author: xirc

atcoder/abc083/D/main.cpp

@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+int count(string const& S) {
+    int const n = S.size();
+    int ans = 0;
+    int i = 0;
+    int l = 0;
+    int m = 0;
+    while (i < n) {
+        if (S[i] == '1') {
+            if (m == 0) l = i;
+            ++m;
+        } else if (m > 0) {
+            int r = n - l - m;
+            int k = min({ n - l, n - r, l + m, m + r });
+            ans = max(ans, k);
+            m = 0;
+        }
+        ++i;
+    }
+    if (m > 0) {
+        int r = n - l - m;
+        int k = min({ n - l, n - r, l + m, m + r });
+        ans = max(ans, k);
+    }
+    return ans;
+}
+
+int solve(string& S) {
+    int ans = count(S);
+    for (int i = 0; i < S.size(); ++i) {
+        S[i] = S[i] == '0' ? '1' : '0';
+    }
+    ans = max(ans, count(S));
+    return ans;
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(0); cout.tie(0);
+
+    string S;
+    cin >> S;
+    cout << solve(S) << endl;
+
+    return 0;
+}