README_EN.md

911. Online Election

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Description

In an election, the i-th vote was cast for persons[i] at time times[i].

Now, we would like to implement the following query function: TopVotedCandidate.q(int t) will return the number of the person that was leading the election at time t.  

Votes cast at time t will count towards our query.  In the case of a tie, the most recent vote (among tied candidates) wins.

 

Example 1:

Input: ["TopVotedCandidate","q","q","q","q","q","q"], [[[0,1,1,0,0,1,0],[0,5,10,15,20,25,30]],[3],[12],[25],[15],[24],[8]]

Output: [null,0,1,1,0,0,1]

Explanation: 

At time 3, the votes are [0], and 0 is leading.

At time 12, the votes are [0,1,1], and 1 is leading.

At time 25, the votes are [0,1,1,0,0,1], and 1 is leading (as ties go to the most recent vote.)

This continues for 3 more queries at time 15, 24, and 8.

 

Note:

1. 1 <= persons.length = times.length <= 5000
2. 0 <= persons[i] <= persons.length
3. times is a strictly increasing array with all elements in [0, 10^9].
4. TopVotedCandidate.q is called at most 10000 times per test case.
5. TopVotedCandidate.q(int t) is always called with t >= times[0].

Solutions

Python3

class TopVotedCandidate:

    def __init__(self, persons: List[int], times: List[int]):
        self.times = times
        mx, cur_win, n = -1, -1, len(persons)
        counter = [0] * (n + 1)
        self.win_persons = [0] * n
        for i, p in enumerate(persons):
            counter[p] += 1
            if counter[p] >= mx:
                mx = counter[p]
                cur_win = p
            self.win_persons[i] = cur_win

    def q(self, t: int) -> int:
        left, right = 0, len(self.win_persons) - 1
        while left < right:
            mid = (left + right + 1) >> 1
            if self.times[mid] <= t:
                left = mid
            else:
                right = mid - 1
        return self.win_persons[left]

# Your TopVotedCandidate object will be instantiated and called as such:
# obj = TopVotedCandidate(persons, times)
# param_1 = obj.q(t)

Java

class TopVotedCandidate {
    private int[] times;
    private int[] winPersons;

    public TopVotedCandidate(int[] persons, int[] times) {
        this.times = times;
        int mx = -1, curWin = -1;
        int n = persons.length;
        int[] counter = new int[n + 1];
        winPersons = new int[n];
        for (int i = 0; i < n; ++i) {
            if (++counter[persons[i]] >= mx) {
                mx = counter[persons[i]];
                curWin = persons[i];
            }
            winPersons[i] = curWin;
        }
    }

    public int q(int t) {
        int left = 0, right = winPersons.length - 1;
        while (left < right) {
            int mid = (left + right + 1) >> 1;
            if (times[mid] <= t) {
                left = mid;
            } else {
                right = mid - 1;
            }
        }
        return winPersons[left];
    }
}

/**
 * Your TopVotedCandidate object will be instantiated and called as such:
 * TopVotedCandidate obj = new TopVotedCandidate(persons, times);
 * int param_1 = obj.q(t);
 */

C++

class TopVotedCandidate {
public:
    vector<int> times;
    vector<int> winPersons;

    TopVotedCandidate(vector<int>& persons, vector<int>& times) {
        this->times = times;
        int mx = -1, curWin = -1;
        int n = persons.size();
        vector<int> counter(n + 1);
        winPersons.resize(n);
        for (int i = 0; i < n; ++i)
        {
            if (++counter[persons[i]] >= mx)
            {
                mx = counter[persons[i]];
                curWin = persons[i];
            }
            winPersons[i] = curWin;
        }

    }

    int q(int t) {
        int left = 0, right = winPersons.size() - 1;
        while (left < right)
        {
            int mid = (left + right + 1) >> 1;
            if (times[mid] <= t) left = mid;
            else right = mid - 1;
        }
        return winPersons[left];
    }
};

/**
 * Your TopVotedCandidate object will be instantiated and called as such:
 * TopVotedCandidate* obj = new TopVotedCandidate(persons, times);
 * int param_1 = obj->q(t);
 */

Go

type TopVotedCandidate struct {
	times      []int
	winPersons []int
}

func Constructor(persons []int, times []int) TopVotedCandidate {
	mx, curWin, n := -1, -1, len(persons)
	counter := make([]int, n+1)
	winPersons := make([]int, n)
	for i, p := range persons {
		counter[p]++
		if counter[p] >= mx {
			mx = counter[p]
			curWin = p
		}
		winPersons[i] = curWin
	}
	return TopVotedCandidate{
		times, winPersons,
	}
}

func (this *TopVotedCandidate) Q(t int) int {
	left, right := 0, len(this.winPersons)-1
	for left < right {
		mid := (left + right + 1) >> 1
		if this.times[mid] <= t {
			left = mid
		} else {
			right = mid - 1
		}
	}
	return this.winPersons[left]
}

/**
 * Your TopVotedCandidate object will be instantiated and called as such:
 * obj := Constructor(persons, times);
 * param_1 := obj.Q(t);
 */

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