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| struct node{ | |
| int val; | |
| void split(node& l, node& r){} | |
| void merge(node& a, node& b) | |
| { | |
| val = min( a.val, b.val ); | |
| } | |
| }tree[1<<(n+1)]; | |
| node range_query(int root, int left_most_leaf, int right_most_leaf, int u, int v) | |
| { | |
| //query the interval [u,v), ie, {x:u<=x<v} | |
| //the interval [left_most_leaf,right_most_leaf) is | |
| //the set of all leaves descending from "root" | |
| if(u<=left_most_leaf && right_most_leaf<=v) | |
| return tree[root]; | |
| int mid = (left_most_leaf+right_most_leaf)/2, | |
| left_child = root*2, | |
| right_child = left_child+1; | |
| tree[root].split(tree[left_child], tree[right_child]); | |
| node l=identity, r=identity; | |
| //identity is an element such that merge(x,identity) = merge(identity,x) = x for all x | |
| if(u < mid) l = range_query(left_child, left_most_leaf, mid, u, v); | |
| if(v > mid) r = range_query(right_child, mid, right_most_leaf, u, v); | |
| tree[root].merge(tree[left_child],tree[right_child]); | |
| node n; | |
| n.merge(l,r); | |
| return n; | |
| } | |
| void mergeup(int postn) | |
| { | |
| postn >>=1; | |
| while(postn>0) | |
| { | |
| tree[postn].merge(tree[postn*2],tree[postn*2+1]); | |
| postn >>=1; | |
| } | |
| } | |
| void update(int pos, node new_val) | |
| { | |
| pos+=(1<<n); | |
| tree[pos]=new_val; | |
| mergeup(pos); | |
| } |
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It should be range_query on line 22 and 23 instead of query.