3015. [Usaco2012 Nov]Concurrently Balanced Strings

BZOJ/3015/3015.cpp

@@ -0,0 +1,81 @@
+#include <iostream>
+#include <algorithm>
+#include <stack>
+#include <string>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 50005;
+const int hash = 1000003;
+const int mod = 1e9 + 7;
+
+int k, n, a[15][N], s[15][N], e[N], next[15][N], ans;
+std::vector<int> nums, p[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> k >> n;
+
+    for (int i = 1; i <= k; i++) {
+        std::string str;
+
+        cin >> str;
+
+        for (int j = 1; j <= n; j++) {
+            a[i][j] = str[j - 1] == '(' ? 1 : -1;
+            s[i][j] = s[i][j - 1] + a[i][j];
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= k; j++) {
+            e[i] = ((static_cast<long long>(e[i]) * hash % mod + s[j][i]) % mod + mod) % mod;
+        }
+
+        nums.push_back(e[i]);
+    }
+
+    std::sort(nums.begin(), nums.end());
+    nums.erase(std::unique(nums.begin(), nums.end()), nums.end());
+
+    p[0].emplace_back(0);
+
+    for (int i = 1; i <= n; i++) {
+        e[i] = std::lower_bound(nums.begin(), nums.end(), e[i]) - nums.begin() + 1;
+        p[e[i]].emplace_back(i);
+    }
+
+    for (int i = 1; i <= k; i++) {
+        std::stack<int> st;
+
+        for (int j = 1; j <= n; j++) {
+            while (!st.empty() && s[i][st.top()] > s[i][j]) {
+                next[i][st.top()] = j;
+                st.pop();
+            }
+
+            st.emplace(j);
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        int min = n;
+
+        for (int j = 1; j <= k; j++) {
+            if (next[j][i]) {
+                min = std::min(min, next[j][i]);
+            }
+        }
+
+        ans += std::upper_bound(p[e[i]].begin(), p[e[i]].end(), min) - std::lower_bound(p[e[i]].begin(), p[e[i]].end(), i + 1);
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}