#929. [2019.10长郡集训day12]古代龙人的谜题（puzzle）

https://sjzezoj.com/submission/55108

S2OJ/929/929.cpp

@@ -0,0 +1,48 @@
+#include <iostream>
+#include <string>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e6 + 5;
+
+int t, n;
+int cnt, len[N];
+int cnt_odd, cnt_even;
+std::string s;
+long long ans;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> t >> n >> s;
+
+    s = ' ' + s;
+
+    len[0] = 1;
+    for (int i = 1; i <= n; i++) {
+        len[s[i] == '1' ? ++cnt : cnt]++;
+    }
+
+    for (int i = 1; i <= cnt; i++) {
+        if (i % 2 == 1) {
+            ans += static_cast<long long>(cnt_even) * len[i];
+            cnt_even += len[i - 1];
+        } else {
+            ans += static_cast<long long>(cnt_odd) * len[i];
+            cnt_odd += len[i - 1];
+        }
+    }
+
+    for (int i = 1; i <= cnt; i++) {
+        if (len[i - 1] > 1 && len[i] > 1) {
+            ans += static_cast<long long>(len[i - 1] - 1) * (len[i] - 1);
+        }
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}