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pojcs101_M01328_radar_greedy_WRONG.cpp

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+#include <iostream>
+#include <vector>
+#include <cmath>
+#include <algorithm>
+
+
+using namespace std;
+
+double other_leg(const double leg, const double diag) {
+    return sqrt(diag * diag - leg * leg);
+}
+
+double diag(const double leg1, const double leg2) {
+    return sqrt(leg1 * leg1 + leg2 * leg2);
+}
+
+int required_radars(vector<pair<int, int>> islands, int distance) {
+    for (auto& [island_x, island_y] : islands) {
+        if (island_y > distance) { return -1; }
+    }
+    sort(islands.begin(), islands.end());
+    int answer = 0;
+    while (!islands.empty()) {
+        answer++;
+        const auto current_island = islands.back();
+        islands.pop_back();
+        double min_x = current_island.first
+            - other_leg(current_island.second, distance)
+            - current_island.second;
+        vector<pair<int, int>> uncovered_islands;
+        while (!islands.empty() && islands.back().first >= min_x) {
+            // 右移雷达
+            const double offset = other_leg(islands.back().second, distance);
+            if (islands.back().first - offset >= min_x) {
+                min_x = islands.back().first - offset;
+            } else {
+                uncovered_islands.push_back(islands.back());
+            }
+            islands.pop_back();
+        }
+        for (int i = uncovered_islands.size() - 1; i >= 0; i--) { // NOLINT(*-narrowing-conversions)
+            islands.push_back(uncovered_islands[i]);
+        }
+    }
+    return answer;
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int n, distance, case_id = 0;
+    while (cin >> n >> distance) {
+        if (n == 0 && distance == 0) { break; }
+        vector<pair<int, int>> islands(n);
+        for (int i = 0; i < n; i++) {
+            cin >> islands[i].first >> islands[i].second;
+        }
+        cout << "Case " << ++case_id << ": " << required_radars(islands, distance) << endl;
+    }
+}