leetcode/Problems/0853.cpp at master · DimitrijeDobrota/leetcode · GitHub

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class Solution {
  public:
    int carFleet(int target, vector<int> &position, vector<int> &speed) {
        int n = position.size();
        if (!n) return 0;
        vector<pair<int, double>> vp(n + 1);

        for (int i = 0; i < n; i++)
            vp[i] = {position[i], (double)(target - position[i]) / speed[i]};
        sort(vp.rbegin(), vp.rend());

        int res = 0;
        double ct = 0;
        for (int i = 0; i < n; i++) {
            auto [_, time] = vp[i];
            if (time > ct) {
                res++;
                ct = time;
            }
        }
        return res;
    }
};

// Using map for the heavy lifting
class Solution {
  public:
    int carFleet(int target, vector<int> &position, vector<int> &speed) {
        map<int, double> mp;

        for (int i = 0; i < speed.size(); i++)
            mp[-position[i]] = (double)(target - position[i]) / speed[i];

        int res = 0;
        double ct = 0;
        for (auto [_, time] : mp) {
            if (time > ct) {
                res++;
                ct = time;
            }
        }
        return res;
    }
};