#include #include using namespace std; const int MAXINDEX = 100005; int tree[MAXINDEX]; // BIT array // Point update for BIT (add val to index idx) void update(int idx, int val) { while (idx < MAXINDEX) { tree[idx] += val; idx += (idx & -idx); } } // Range update: add val to range [l, r] void range_update(int l, int r, int val) { update(l, val); // Add val at start update(r + 1, -val); // Remove val after end } // Point query: get value at index idx int point_query(int idx) { int res = 0; while (idx> 0) { res += tree[idx]; idx -= (idx & -idx); } return res; } // Example usage int main() { // Range updates range_update(2, 5, 10); // add 10 to all elements in [2, 5] range_update(4, 7, 5); // add 5 to all elements in [4, 7] // Point queries cout << "Value at index 3: " << point_query(3) << endl; // should print 10 cout << "Value at index 5: " << point_query(5) << endl; // should print 15 cout << "Value at index 7: " << point_query(7) << endl; // should print 5 cout << "Value at index 1: " << point_query(1) << endl; // should print 0 return 0; }