lintcode-区间最小数-205

class SegmentTreeNode {
public int start, end, min;
public SegmentTreeNode left, right;
public SegmentTreeNode(int start, int end) {
this.start = start;
this.end = end;
this.min = 0;
this.left = this.right = null;
}
}
public class Solution {

public SegmentTreeNode build(int start, int end, int[] A) {

if(start > end) {
return null;
}

SegmentTreeNode root = new SegmentTreeNode(start, end);

if(start != end) {
int mid = (start + end) / 2;
root.left = build(start, mid, A);
root.right = build(mid+1, end, A);
root.min = Math.min(root.left.min, root.right.min);
} else {
root.min = A[start];
}
return root;
}
public int query(SegmentTreeNode root, int start, int end) {

if(start <= root.start && root.end <= end) {
return root.min;
}

int mid = (root.start + root.end)/2;

if(start>mid)
return query(root.right,start,end);

else if(mid+1>end)
return query(root.left, start, end);

else
return Math.min(query(root.left,start,mid),query(root.right,mid+1,end));
}

public ArrayList<Integer> intervalMinNumber(int[] A,
ArrayList<Interval> queries) {
SegmentTreeNode root = build(0, A.length - 1, A);
ArrayList ans = new ArrayList<Integer>();
for(Interval in : queries) {
ans.add(query(root, in.start, in.end));
}
return ans;
}
}