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- int arr[mx];
- int tree[mx * 3];
- void init(int node, int b, int e){
- if (b == e) {
- tree[node] = arr[b];
- return;
- }
- int Left = node * 2;
- int Right = node * 2 + 1;
- int mid = (b + e) / 2;
- init(Left, b, mid);
- init(Right, mid + 1, e);
- tree[node] = tree[Left] + tree[Right];
- }
- int query(int node, int b, int e, int i, int j){
- if (i > e || j < b)
- return 0;
- if (b >= i && e <= j)
- return tree[node];
- int Left = node * 2;
- int Right = node * 2 + 1;
- int mid = (b + e) / 2;
- int p1 = query(Left, b, mid, i, j);
- int p2 = query(Right, mid + 1, e, i, j);
- return p1 + p2;
- }
- void update(int node, int b, int e, int i, int newvalue){
- if (i > e || i < b)
- return;
- if (b >= i && e <= i) {
- tree[node] = newvalue;
- return;
- }
- int Left = node * 2;
- int Right = node * 2 + 1;
- int mid = (b + e) / 2;
- update(Left, b, mid, i, newvalue);
- update(Right, mid + 1, e, i, newvalue);
- tree[node] = tree[Left] + tree[Right];
- }
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