2025“钉耙编程”中国大学生算法设计暑期联赛（3）

Author: Macesuted

HDOJ/1174-1004.cpp

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+/**
+ * @file 1174-1004.cpp
+ * @author Macesuted (i@macesuted.moe)
+ * @date 2025-07-25
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int a[15], A[15], B[15], id[15];
+
+void solve(void) {
+    int n = 13;
+    for (int i = 1; i <= n; i++) cin >> a[i];
+
+    auto check = [&](int lim) -> bool {
+        int sumA = 0, sumB = 0;
+        for (int i = 1; i <= n; i++) {
+            A[i] = min({a[i] / 3, lim}), sumA += A[i];
+            B[i] = min({a[i] - 3 * A[i], lim - A[i]}), sumB += B[i];
+        }
+        if (sumA < lim) return false;
+
+        for (int i = 1; i <= n; i++) id[i] = i;
+
+        sort(id + 1, id + n + 1, [&](int x, int y) { return (lim - A[x] - B[x]) / 2 > (lim - A[y] - B[y]) / 2; });
+        for (int p = 1; p <= n; p++) {
+            int i = id[p], x = min({sumA - lim, (lim - A[i] - B[i]) / 2, A[i]});
+            A[i] -= x, sumA -= x;
+            B[i] += 3 * x, sumB += 3 * x;
+        }
+
+        sort(id + 1, id + n + 1, [&](int x, int y) { return lim - A[x] - B[x] > lim - A[y] - B[y]; });
+        for (int p = 1; p <= n; p++) {
+            int i = id[p], x = min({sumA - lim, lim - A[i] - B[i], A[i]});
+            A[i] -= x, sumA -= x;
+            B[i] += 2 * x, sumB += 2 * x;
+        }
+
+        for (int i = 1; i <= n; i++) {
+            int x = min(sumA - lim, A[i]);
+            A[i] -= x, sumA -= x;
+            B[i] += x, sumB += x;
+        }
+
+        return sumB >= lim;
+    };
+
+    int l = 0, r = 1e7;
+    while (l + 1 < r) {
+        int mid = (l + r) >> 1;
+        (check(mid) ? l : r) = mid;
+    }
+
+    cout << l << endl;
+
+    return;
+}
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr);
+
+    int _ = 1;
+    cin >> _;
+    while (_--) solve();
+
+    return 0;
+}

HDOJ/1174-1007.cpp

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+/**
+ * @file 1174-1007.cpp
+ * @author Macesuted (i@macesuted.moe)
+ * @date 2025-07-25
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define endl '\n'
+
+mt19937_64 rnd(114514);
+
+void solve(void) {
+    int n;
+    cin >> n;
+
+    map<int, uint64_t> delt;
+    for (int i = 1, l, r; i <= n; i++) {
+        cin >> l >> r;
+        uint64_t v = rnd();
+        delt[l] ^= v, delt[r + 1] ^= v;
+    }
+
+    set<uint64_t> S;
+    S.insert(0);
+    uint64_t cur = 0;
+    for (auto [x, v] : delt) S.insert(cur ^= v);
+
+    cout << S.size() << endl;
+
+    return;
+}
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr);
+
+    int _ = 1;
+    cin >> _;
+    while (_--) solve();
+
+    return 0;
+}

HDOJ/1174-1008.cpp

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+/**
+ * @file 1174-1008.cpp
+ * @author Macesuted (i@macesuted.moe)
+ * @date 2025-07-25
+ *
+ * @copyright Copyright (c) 2025
+ *
+ */
+
+#include <bits/stdc++.h>
+using namespace std;
+
+#define endl '\n'
+#define maxn 1000005
+
+int a[maxn];
+
+void solve(void) {
+    int n;
+    string s;
+    cin >> n >> s;
+
+    for (int i = 1; i <= n; i++) a[i] = (s[i - 1] - '0') ^ (i & 1);
+
+    vector<int> rec;
+    for (int l = 1, r; l <= n; l = r + 1) {
+        r = l;
+        while (r + 1 <= n && a[l] == a[r + 1]) r++;
+        rec.push_back(r - l + 1);
+    }
+
+    if (rec.size() == 1) return cout << 0 << endl, void();
+    if (rec.size() & 1) rec.front() += rec.back(), rec.pop_back();
+    int cur[2] = {0, 0};
+    for (int i = 0; i < (int)rec.size(); i++) cur[i & 1] += (rec[i] + 1) / 2;
+    cout << min(cur[0], cur[1]) << endl;
+
+    return;
+}
+
+int main() {
+    ios::sync_with_stdio(false), cin.tie(nullptr);
+
+    int _ = 1;
+    cin >> _;
+    while (_--) solve();
+
+    return 0;
+}