51Nod 1174区间中最大的数

题目链接：https://www.51nod.com/onlineJudge/questionCode.html#!problemId=1174

import java.util.Scanner;

public class Main{

static int N = 10000;
static TNode[] q = new TNode[N*4];
static int[] a = new int
;
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
for(int i = 0; i < n; i++) {
a[i] = scanner.nextInt();
}
build(0, 0, n-1);
//查询的个数
int m = scanner.nextInt();
for(int i = 0; i < m; i++) {
int left = scanner.nextInt();
int right = scanner.nextInt();
int tmp = query(0,0,n-1, left, right);
System.out.println(tmp);
}
}
public static void build(int i,int left,int right) {
q[i] = new TNode();
q[i].mark = 0;
if (left == right) {
q[i].val = a[left];
} else {
int mid = (left + right) / 2;
build(i*2+1, left, mid);
build(i*2+2, mid+1, right);
q[i].val = Math.max(q[i*2+1].val, q[i*2+2].val);
}
}
public static void pushDown(int i) {
if(q[i].mark != 0) {
q[i*2+1].mark += q[i].mark;
q[i*2+2].mark += q[i].mark;

q[i*2+1].val += q[i].mark;
q[i*2+2].val += q[i].mark;

q[i].mark = 0;
}
}
public static int query(int i,int nstart,int nend,int left,int right) {
if(nend < left || right < nstart) {
return -1;
}
//当前节点区间包含在查询区间内
if(left <= nstart && right >= nend) {
return q[i].val;
}

pushDown(i);
int mid = (nstart + nend) / 2;
return Math.max(query(i*2+1,nstart,mid, left, right), query(i*2+2,mid+1,nend, left, right));
}
}
class TNode {
int mark;
int val;
}