Question

911. Online Election

中文文档

Description

You are given two integer arrays persons and times. In an election, the ith vote was cast for persons[i] at time times[i].

For each query at a time t, find 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.

Implement the TopVotedCandidate class:

• TopVotedCandidate(int[] persons, int[] times) Initializes the object with the persons and times arrays.
• int q(int t) Returns the number of the person that was leading the election at time t according to the mentioned rules.

 

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
TopVotedCandidate topVotedCandidate = new TopVotedCandidate([0, 1, 1, 0, 0, 1, 0], [0, 5, 10, 15, 20, 25, 30]);
topVotedCandidate.q(3); // return 0, At time 3, the votes are [0], and 0 is leading.
topVotedCandidate.q(12); // return 1, At time 12, the votes are [0,1,1], and 1 is leading.
topVotedCandidate.q(25); // return 1, At time 25, the votes are [0,1,1,0,0,1], and 1 is leading (as ties go to the most recent vote.)
topVotedCandidate.q(15); // return 0
topVotedCandidate.q(24); // return 0
topVotedCandidate.q(8); // return 1

 

Constraints:

• 1 <= persons.length <= 5000
• times.length == persons.length
• 0 <= persons[i] < persons.length
• 0 <= times[i] <= 109
• times is sorted in a strictly increasing order.
• times[0] <= t <= 109
• At most 104 calls will be made to q.

Solutions

Solution 1

class TopVotedCandidate:
  def __init__(self, persons: List[int], times: List[int]):
    mx = cur = 0
    counter = Counter()
    self.times = times
    self.wins = []
    for i, p in enumerate(persons):
      counter[p] += 1
      if counter[p] >= mx:
        mx, cur = counter[p], p
      self.wins.append(cur)

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


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

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);
 */

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

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

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

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

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

func Constructor(persons []int, times []int) TopVotedCandidate {
  mx, cur, n := 0, 0, len(persons)
  counter := make([]int, n)
  wins := make([]int, n)
  for i, p := range persons {
    counter[p]++
    if counter[p] >= mx {
      mx = counter[p]
      cur = p
    }
    wins[i] = cur
  }
  return TopVotedCandidate{times, wins}
}

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

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