백준 커피숍2

https://www.acmicpc.net/problem/1275

1275번: 커피숍2

쉽네여~

import java.util.*;
import java.io.*;
public class Main {
	public static long tree[];

	public static long buildingTree(int start,int end ,int node, long arr[]){
		if(start==end){
			return tree[node]=arr[start];
		}
		int mid=(start+end)/2;
		return tree[node]=buildingTree(start,mid,node*2,arr)+buildingTree(mid+1,end,node*2+1,arr);
	}

	public static void update( int start, int end, int node, long newValue, int findIndex){
		if(  end < findIndex  || findIndex < start){
			return;
		}

		if(start==end){
			tree[node]=newValue;
			return;
		}

		int mid=(start+end)/2;

		update( start, mid,node*2, newValue, findIndex);

		update(mid+1, end,node*2+1, newValue, findIndex);

		tree[node]=tree[node*2]+tree[node*2+1];
	}

	public static long select(int start ,int end, int node, int left, int right){
		if( left > end|| right < start ){
			return 0;
		}

		if( left<= start && end<=right ){
			return tree[node];
		}

		int mid=(start+end)/2;
		return select(start,mid,node*2,left,right)+select(mid+1,end,node*2+1,left,right);
	}

	public static void main(String[] args) throws Exception {
		Scanner scan = new Scanner(System.in);
		int n=scan.nextInt();
		int m=scan.nextInt();
		long arr[]=new long[n];
		tree=new long[n*4];
		for(int i=0;i<n;i++){
			long tmp=scan.nextLong();
			arr[i]=tmp;
		}
		buildingTree(0,n-1,1,arr);

		for(int i=0; i<m; i++ ){
			int x=scan.nextInt();
			int y=scan.nextInt();
			int a=scan.nextInt();
			long b=scan.nextLong();
			if(x>y){
				int tmp=y;
				y=x;
				x=tmp;
			}
			long sum=select(0,n-1,1,x-1,y-1);
			update(0,n-1,1, b,a-1);
			System.out.println(sum);
		}

	}
}