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  1. //
  2. // main.cpp
  3. // practice
  4. //
  5. // Created by Mahmud on 9/13/17.
  6. // Copyright © 2017 Mahmud. All rights reserved.
  7. //
  8.  
  9. /*
  10. An O((N + Q) * log(N)) solution using implicit segment trees
  11. Data values are compressed to get rid of log(N) factor.
  12. */
  13.  
  14. #include <iostream>
  15. #include <cstdio>
  16. #include <algorithm>
  17. #include <vector>
  18.  
  19. using namespace std;
  20.  
  21. const int MAX = 200005;
  22.  
  23. int N, Q;
  24. int data[MAX];
  25. int position[MAX], value[MAX];
  26.  
  27. struct node {
  28. int sum;
  29. node *l;
  30. node *r;
  31. node () {
  32.  
  33. }
  34. };
  35. typedef node * pnode;
  36.  
  37. int getValue (pnode p) {
  38. return p ? p->sum : 0;
  39. }
  40. pnode initialize (int value) {
  41. pnode p = pnode(malloc(sizeof(node)));
  42. p->sum = value;
  43. p->l = NULL;
  44. p->r = NULL;
  45. return p;
  46. }
  47. void updatePosition (pnode &root, int low, int high, int position, int value) {
  48. if (!root) {
  49. root = initialize(0);
  50. }
  51. if (low == high) {
  52. root->sum += value;
  53. return;
  54. }
  55. int middle = (low + high) >> 1;
  56. if (position <= middle) {
  57. updatePosition(root->l, low, middle, position, value);
  58. }
  59. else {
  60. updatePosition(root->r, middle + 1, high, position, value);
  61. }
  62. root->sum = getValue(root->l) + getValue(root->r);
  63. }
  64. int getInRange (pnode &root, int low, int high, int l, int r) {
  65. if (!root) {
  66. return 0;
  67. }
  68. if (low > r || high < l) {
  69. return 0;
  70. }
  71. if (low >= l && high <= r) {
  72. return root->sum;
  73. }
  74. int middle = (low + high) >> 1;
  75. return getInRange(root->l, low, middle, l, r)
  76. + getInRange(root->r, middle + 1, high, l, r);
  77. }
  78.  
  79. pnode pool[MAX << 1];
  80.  
  81. int main(int argc, const char * argv[]) {
  82. scanf("%d%d", &N, &Q);
  83. for (int i = 0; i < N; i ++) {
  84. scanf("%d", &data[i]);
  85. }
  86. for (int i = 0; i < Q; i ++) {
  87. scanf("%d%d", &position[i], &value[i]);
  88. }
  89. vector<int> items = vector<int> (data, data + N);
  90. items.insert(items.end(), value, value + Q);
  91. sort(items.begin(), items.end());
  92. items.erase(unique(items.begin(), items.end()), items.end());
  93.  
  94. for (int i = 0; i < N; i ++) {
  95. data[i] = (int)(lower_bound(items.begin(), items.end(), data[i]) - items.begin());
  96. }
  97. for (int i = 0; i < Q; i ++) {
  98. value[i] = (int)(lower_bound(items.begin(), items.end(), value[i]) - items.begin());
  99. }
  100. for (int i = 0; i < N; i ++) {
  101. updatePosition(pool[data[i]], 1, N, i + 1, 1);
  102. }
  103. for (int i = 0; i < Q; i ++) {
  104. printf("%d\n", getInRange(pool[value[i]], 1, N, 1, position[i]));
  105. if (data[position[i]] != value[i]) {
  106. updatePosition(pool[data[position[i]]], 1, N, position[i] + 1, -1);
  107. data[position[i]] = value[i];
  108. updatePosition(pool[data[position[i]]], 1, N, position[i] + 1, 1);
  109. }
  110. }
  111.  
  112. return 0;
  113. }
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