Segment Tree

##线段树

class Node{
    int left, right;
    int sum;
};
int N;
vector<Node> tree;

void BuildTree(){
    
}

http://www.cnblogs.com/superbin/archive/2010/08/02/1790467.html
http://blog.csdn.net/bochuan007/article/details/6713971
http://blog.csdn.net/metalseed/article/details/8039326
http://blog.csdn.net/x314542916/article/details/7837276
http://www.doc88.com/p-790936693134.html