线段树

线段树的构建与查询

void build_tree(int left, int right, int i) {
	if(left == right) {
		int val;
		scanf("%d", &val);
		n[i].nmax = n[i].nmin = val;
		return ;
	}
	int mid = (left + right) / 2;
	build_tree(left, mid, i << 1);
	build_tree(mid + 1, right, i << 1 | 1);
	n[i].nmax = max(n[i << 1].nmax, n[i << 1 | 1].nmax);
	n[i].nmin = min(n[i << 1].nmin, n[i << 1 | 1].nmin);
}

void search_tree(int left, int right, int tleft, int tright, int i) {
	if(left == tleft && right == tright) {
		if(MAX < n[i].nmax)
			MAX = n[i].nmax;
		if(MIN > n[i].nmin)
			MIN = n[i].nmin;
		return ;
	}
	int mid = (tleft + tright) / 2;
	if(right <= mid)
		search_tree(left, right, tleft, mid, i << 1);
	else if(left >= mid + 1)
		search_tree(left, right, mid + 1, tright, i << 1 | 1);
	else {
		search_tree(left, mid, tleft, mid, i << 1);
		search_tree(mid + 1, right, mid + 1, tright, i << 1 | 1);
	}
}