蓝桥杯 算法训练 操作格子 JAVA

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.PrintWriter;import java.util.StringTokenizer;public class Main {PrintWriter out = new PrintWriter(System.out);InputReader cin = new InputReader(System.in);final static int MAX_N = 100007;class Node {int l, r;int sum, max;Node () {}Node (int l, int r, int sum, int max) {this.l = l;this.r = r;this.sum = sum;this.max = max;}}int n, m;Node tree[] = new Node[MAX_N << 2];int a[] = new int[MAX_N];void up(int id) {tree[id].sum = tree[id << 1].sum + tree[id << 1 | 1].sum;tree[id].max = Math.max(tree[id << 1].max, tree[id << 1| 1].max);}void build(int id, int l, int r) {tree[id] = new Node(l, r, 0, 0);if (l == r) {tree[id].sum = tree[id].max = a[l];return ;}int mid = (l + r) >> 1;build(id << 1, l, mid);build(id << 1 | 1, mid + 1, r);up(id);}void update(int id, int pos, int val) {if (tree[id].l == tree[id].r) {tree[id].sum = tree[id].max = val;return ;}int mid = (tree[id].l + tree[id].r) >> 1;if (pos <= mid) update(id << 1, pos, val);else update(id << 1 | 1, pos, val);up(id);}int sum(int id, int l, int r) {if (l <= tree[id].l && tree[id].r <= r) {return tree[id].sum;}int mid = (tree[id].l + tree[id].r) >> 1;if (r <= mid) return sum(id << 1, l, r);else if (l > mid) return sum(id << 1 | 1, l, r);else {return sum(id << 1, l, mid) + sum(id << 1 | 1, mid + 1, r);}}int max(int id, int l, int r) {if (l <= tree[id].l && tree[id].r <= r) {return tree[id].max;}int mid = (tree[id].l + tree[id].r) >> 1;if (r <= mid) return max(id << 1, l, r);else if (l > mid) return max(id << 1 | 1, l, r);else {return Math.max(max(id << 1, l, mid), max(id << 1 | 1, mid + 1, r));}}void run() throws IOException {n = cin.nextInt();m = cin.nextInt();for (int i = 1; i <= n; ++i)a[i] = cin.nextInt();build(1, 1, n);for (int i = 0; i < m; ++i) {int type = cin.nextInt();int l = cin.nextInt();int r = cin.nextInt();if (type == 1) update(1, l, r);else if (type == 2) out.println(sum(1, l, r));else out.println(max(1, l, r));}out.close(); }public static void main(String[] args) throws IOException {new Main().run();}class InputReader {private BufferedReader reader;private StringTokenizer tokenizer;InputReader(InputStream in) {reader = new BufferedReader(new InputStreamReader(in));tokenizer = new StringTokenizer("");}private String next() throws IOException {while (!tokenizer.hasMoreTokens()) {tokenizer = new StringTokenizer(reader.readLine());}return tokenizer.nextToken();}public Integer nextInt() throws IOException {return Integer.parseInt(next());}}}