C - Menorah

https://codeforces.com/contest/1615/submission/140490176

CodeForces/1615/C/C.cpp

@@ -0,0 +1,46 @@
+#include <iostream>
+#include <string>
+
+using std::cin;
+using std::cout;
+using std::endl;
+
+int main() {
+    int t;
+    cin >> t;
+    while (t--) {
+        int n, cnt1 = 0, cnt2 = 0;
+        std::string a, b;
+        cin >> n >> a >> b;
+        for (char c : a) {
+            cnt1 += c == '1';
+        }
+        for (char c : b) {
+            cnt2 += c == '1';
+        }
+        if (cnt1 != cnt2 && n - cnt1 + 1 != cnt2) {
+            cout << -1 << endl;
+            continue;
+        }
+        int m0 = 0, m1 = 0;
+        for (int i = 0; i < n; i++) {
+            if (b[i] == '1') {
+                if (a[i] == '0') {
+                    m0++;
+                } else {
+                    m1++;
+                }
+            }
+        }
+        int a1 = (cnt2 - m1) * 2,
+            a2 = (cnt2 - m0) * 2 - 1;
+        if (cnt1 != cnt2) {
+            cout << a2 << endl;
+        } else if (n - cnt1 + 1 != cnt2) {
+            cout << a1 << endl;
+        } else {
+            cout << std::min(a1, a2) << endl;
+        }
+    }
+    return 0;
+}