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| #include <stdio.h>
#define MAXL 100005
void build_tree(int arr[], int tree[], int node, int start, int end)
{
if (start == end) {
tree[node] = arr[start];
return;
}
int mid = (start + end) / 2;
int left_node = node * 2 + 1;
int right_node = node * 2 + 2;
build_tree(arr, tree, left_node, start, mid);
build_tree(arr, tree, right_node, mid + 1, end);
tree[node] = tree[left_node] + tree[right_node];
}
void update_tree(int arr[], int tree[], int node, int start, int end, int index, int val)
{
if (start == end) {
arr[index] = val;
tree[node] = val;
return;
}
int mid = (start + end) / 2;
int left_node = 2 * node + 1;
int right_node = 2 * node + 2;
if (index >= start && index <= mid) {
update_tree(arr, tree, left_node, start, mid, index, val);
} else {
update_tree(arr, tree, right_node, mid + 1, end, index, val);
}
tree[node] = tree[left_node] + tree[right_node];
}
int query_tree(int arr[], int tree[], int node, int start, int end, int l, int r)
{
if (r < start || l > end) {
return 0;
}else if(start == end || (start>=l&&end<=r)){
return tree[node];
}
int mid = (start + end) / 2;
int left_node = 2 * node + 1;
int right_node = 2 * node + 2;
int sum_left = query_tree(arr, tree, left_node, start, mid, l, r);
int sum_right = query_tree(arr, tree, right_node, mid + 1, end, l, r);
return sum_left + sum_right;
}
int main()
{
int arr[] = { 1, 3, 5, 7, 9, 11 };
int size = 6;
int tree[MAXL] = { 0 };
build_tree(arr, tree, 0, 0, size - 1);
for (int i = 0; i < 15; i++) {
printf("tree[%d]=%d\n", i, tree[i]);
}
puts("");
update_tree(arr, tree, 0, 0, 5, 4, 6);
for (int i = 0; i < 15; i++) {
printf("tree[%d]=%d\n", i, tree[i]);
}
printf("%d",query_tree(arr, tree, 0, 0, 5, 2, 5));
return 0;
}
|
