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2026-07-29 22:53:24 +05:00
parent 8bc1b22a1c
commit f853068f9b
5 changed files with 146 additions and 15 deletions
@@ -0,0 +1,55 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+typedef pair<int, int> Range;
+typedef pair<int, int> FuelStop;
+
+vector<Range> covered_ranges(const vector<FuelStop>& fuel_stops, const int full_distance, const int initial_fuel) {
+    vector<Range> ranges{{0, initial_fuel}};
+    ranges.reserve(fuel_stops.size());
+    for (const auto& [distance, fuel_amount] : fuel_stops) {
+        ranges.emplace_back(full_distance - distance, full_distance - distance + fuel_amount);
+    }
+    return ranges;
+}
+
+int min_stops(vector<Range> ranges, const int full_distance) {
+    sort(ranges.begin(), ranges.end());
+    int answer = 0;
+    int current_pos = 0, max_r = -1;
+    for (int i = 0; i < ranges.size();) {
+        if (ranges[i].first <= current_pos) {
+            max_r = max(max_r, ranges[i].second);
+            if (max_r >= full_distance) { return answer - 1; }
+            i++;
+        } else {
+            if (max_r < current_pos) { return -1; }
+            answer++, current_pos = max_r, max_r = -1;
+        }
+    }
+    return -1;
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+    int fuel_stop_count, full_distance, initial_fuel;
+    cin >> fuel_stop_count;
+    vector<FuelStop> fuel_stops(fuel_stop_count);
+    for (int i = 0; i < fuel_stop_count; i++) {
+        cin >> fuel_stops[i].first >> fuel_stops[i].second;
+    }
+    cin >> full_distance >> initial_fuel;
+    const vector<Range> ranges = covered_ranges(fuel_stops, full_distance, initial_fuel);
+    for (const auto& [l, r] : ranges) {
+        clog << "[" << l << "," << r << "] ";
+    }
+    clog << endl;
+
+    cout << min_stops(ranges, full_distance) << endl;
+
+    return 0;
+}