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Author: MathProgrammer

C Programs/C Programs - 3/D-Query.cpp

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+#include <bits/stdc++.h>
+
+using namespace std;
+
+#define all(v) (v).begin(), (v).end()
+#define LEFT(n) (n << 1)
+#define RIGHT(n) ( (n << 1)|1 )
+
+const int INSERTION = 0, QUERY = 1, MAX_N = 1e6 + 5, OLD_LAST_OCCURENCE = 0, NEW_LAST_OCCURENCE = 1;
+int tree[3*MAX_N];
+
+struct info
+{
+    int end;
+    int type;
+    int position, value;
+    int left, right, query_no;
+
+    info(){ end = type = left = right = query_no = position = -1; }
+};
+
+int compare_ends(const info &A, const info &B)
+{
+    if(A.end < B.end)
+        return true;
+    else if(A.end == B.end)
+        return (A.type == INSERTION);
+
+    return false;
+}
+
+void insert(int n, int left, int right, int position, int position_type)
+{
+    if(right < position || position < left)
+        return;
+
+    if(left == right)
+    {
+        if(position_type == OLD_LAST_OCCURENCE)
+            tree[n] = 0;
+        else if(position_type == NEW_LAST_OCCURENCE)
+            tree[n] = 1;
+
+        return;
+    }
+
+    int mid = (left + right) >> 1;
+
+    if(position <= mid)
+        insert(LEFT(n), left, mid, position, position_type);
+    else if(position > mid)
+        insert(RIGHT(n), mid + 1, right, position, position_type);
+
+    tree[n] = tree[LEFT(n)] + tree[RIGHT(n)];
+}
+
+int query(int n, int left, int right, int query_left, int query_right)
+{
+   if(query_right < left || right < query_left)
+       return 0;
+
+    if(query_left <= left && right <= query_right)
+        return tree[n];
+
+    int mid = (left + right) >> 1;
+
+    int left_answer = query(LEFT(n), left, mid, query_left, query_right);
+    int right_answer = query(RIGHT(n), mid + 1, right, query_left, query_right);
+
+    return (left_answer + right_answer);
+}
+
+int main()
+{
+    memset(tree, 0, sizeof(tree));
+
+    vector <info> event;
+
+    int no_of_elements;
+    scanf("%d", &no_of_elements);
+    for(int i = 1; i <= no_of_elements; i++)
+    {
+        info current_event;
+        current_event.type = INSERTION;
+        current_event.end = current_event.position = i;
+        scanf("%d", &current_event.value);
+
+        event.push_back(current_event);
+    }
+
+    int no_of_queries;
+    scanf("%d", &no_of_queries);
+    for(int i = 1; i <= no_of_queries; i++)
+    {
+        info current_event;
+        current_event.type = QUERY;
+
+        scanf("%d %d", &current_event.left, &current_event.right);
+        current_event.end = current_event.right;
+        current_event.query_no = i;
+
+        event.push_back(current_event);
+    }
+
+    sort(all(event), compare_ends);
+
+    int no_of_events = no_of_elements + no_of_queries;
+
+    map <int, int> last_occurence;
+    vector <int> answer(no_of_queries + 1);
+
+    for(int i = 0; i < no_of_events; i++)
+    {
+       if(event[i].type == INSERTION)
+       {
+           int element = event[i].value;
+
+           if(last_occurence.count(element) == 1)
+           {
+               insert(1, 1, no_of_elements, last_occurence[element], OLD_LAST_OCCURENCE);
+           }
+
+           insert(1, 1, no_of_elements, event[i].position, NEW_LAST_OCCURENCE);
+           last_occurence[element] = event[i].position;
+       }
+       else if(event[i].type == QUERY)
+       {
+           answer[event[i].query_no] = query(1, 1, no_of_elements, event[i].left, event[i].right);
+       }
+    }
+
+    for(int i = 1; i <= no_of_queries; i++)
+        printf("%d\n", answer[i]);
+
+    return 0;
+}