Question

911. 在线选举

English Version

题目描述

给你两个整数数组 persons 和 times 。在选举中，第 i 张票是在时刻为 times[i] 时投给候选人 persons[i] 的。

对于发生在时刻 t 的每个查询，需要找出在 t 时刻在选举中领先的候选人的编号。

在 t 时刻投出的选票也将被计入我们的查询之中。在平局的情况下，最近获得投票的候选人将会获胜。

实现 TopVotedCandidate 类：

• TopVotedCandidate(int[] persons, int[] times) 使用 persons 和 times 数组初始化对象。
• int q(int t) 根据前面描述的规则，返回在时刻 t 在选举中领先的候选人的编号。

 

示例：

输入：
["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]]
输出：
[null, 0, 1, 1, 0, 0, 1]

解释：
TopVotedCandidate topVotedCandidate = new TopVotedCandidate([0, 1, 1, 0, 0, 1, 0], [0, 5, 10, 15, 20, 25, 30]);
topVotedCandidate.q(3); // 返回 0 ，在时刻 3 ，票数分布为 [0] ，编号为 0 的候选人领先。
topVotedCandidate.q(12); // 返回 1 ，在时刻 12 ，票数分布为 [0,1,1] ，编号为 1 的候选人领先。
topVotedCandidate.q(25); // 返回 1 ，在时刻 25 ，票数分布为 [0,1,1,0,0,1] ，编号为 1 的候选人领先。（在平局的情况下，1 是最近获得投票的候选人）。
topVotedCandidate.q(15); // 返回 0
topVotedCandidate.q(24); // 返回 0
topVotedCandidate.q(8); // 返回 1

 

提示：

• 1 <= persons.length <= 5000
• times.length == persons.length
• 0 <= persons[i] < persons.length
• 0 <= times[i] <= 109
• times 是一个严格递增的有序数组
• times[0] <= t <= 109
• 每个测试用例最多调用 104 次 q

解法

方法一

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);
 */