Problem:
Score : 600 points

Problem Statement

We have N colored balls arranged in a row from left to right; the color of the i-th ball from the left is c_i.

You are given Q queries. The i-th query is as follows: how many different colors do the l_i-th through r_i-th balls from the left have?

Constraints

1\leq N,Q \leq 5 \times 10^5

1\leq c_i \leq N

1\leq l_i \leq r_i \leq N

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N Q
c_1 c_2 \cdots c_N
l_1 r_1
l_2 r_2
:
l_Q r_Q

Output

Print Q lines. The i-th line should contain the response to the i-th query.

Sample Input 1

4 3
1 2 1 3
1 3
2 4
3 3

Sample Output 1

2
3
1

The 1-st, 2-nd, and 3-rd balls from the left have the colors 1, 2, and 1 - two different colors.

The 2-st, 3-rd, and 4-th balls from the left have the colors 2, 1, and 3 - three different colors.

The 3-rd ball from the left has the color 1 - just one color.

Sample Input 2

10 10
2 5 6 5 2 1 7 9 7 2
5 5
2 4
6 7
2 2
7 8
7 9
1 8
6 9
8 10
6 8

Sample Output 2

1
2
2
1
2
2
6
3
3
3

Solution in Python (3.8.2) (judge verdict: Time Limit Exceeded)


import sys
input = sys.stdin.readline
def main():
  n,q=map(int,input().split())
  c=list(map(int,input().split()))
  lr=[list(map(int,input().split())) for _ in range(q)]
  lri=[[lr[i][0],lr[i][1],i] for i in range(q)]
  lri.sort(key=lambda x:x[1])
  def segfunc(x, y):
    return x+y
  #################

  #####ide_ele#####
  ide_ele=0
  #################

  class SegTree:
    """
    init(init_val, ide_ele): 配列init_valで初期化 O(N)
    update(k, x): k番目の値をxに更新 O(logN)
    query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)
    """
    def __init__(self, init_val, segfunc=segfunc, ide_ele=ide_ele):
      """
      init_val: 配列の初期値
      segfunc: 区間にしたい操作
      ide_ele: 単位元
      n: 要素数
      num: n以上の最小の2のべき乗
      tree: セグメント木(1-index)
      """
      n = len(init_val)
      self.segfunc = segfunc
      self.ide_ele = ide_ele
      self.num = 1 << (n - 1).bit_length()
      self.tree = [ide_ele] * 2 * self.num
      # 配列の値を葉にセット
      for i in range(n):
        self.tree[self.num + i] = init_val[i]
      # 構築していく
      for i in range(self.num - 1, 0, -1):
        self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])

    def update(self, k, x):
      """
      k番目の値をxに更新
      k: index(0-index)
      x: update value
      """
      k += self.num
      self.tree[k] = x
      while k > 1:
        self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])
        k >>= 1

    def query(self, l, r):
      """
      [l, r)のsegfuncしたものを得る
      l: index(0-index)
      r: index(0-index)
      """
      res = self.ide_ele

      l += self.num
      r += self.num
      while l < r:
        if l & 1:
          res = self.segfunc(res, self.tree[l])
          l += 1
        if r & 1:
          res = self.segfunc(res, self.tree[r - 1])
        l >>= 1
        r >>= 1
      return res
  st=SegTree([0]*(n+1))
  dc={}
  ans=[0]*q
  j=0
  for i in range(n):
    x=c[i]
    if x in dc:
      st.update(dc[x],0)
    st.update(i+1,1)
    dc[x]=i+1
    while j<q and i+1==lri[j][1]:
      l,r,k=lri[j]
      ans[k]=st.query(l,r+1)
      j+=1
    if j==q:break
  print(*ans,sep='\n')


if __name__=='__main__':
  #import datetime
  #print(datetime.datetime.now())
  main()
  #print(datetime.datetime.now())