[알고리즘] 백준 2003번 : 수들의 합2 (실버3)

 

문제

https://www.acmicpc.net/problem/2003

 

 

📌 문제풀이

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;
class Main {	
	public static void main(String[] args) throws IOException{
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		String firtLine = br.readLine();
		
		StringTokenizer st = new StringTokenizer(firtLine, " ");
		
		// 수열 개수
		int N = Integer.parseInt(st.nextToken());
		
		int[] arr = new int[N];
		
		// 합
		int M = Integer.parseInt(st.nextToken());
		
		
		String secondLine = br.readLine();
		
		st = new StringTokenizer(secondLine, " ");


		for(int i=0; i<N; i++) {
			arr[i] = Integer.parseInt(st.nextToken());
		}
		
		int start = 0;
		int end = 0;
		int sum = 0;
		int count = 0;

		
		// 투 포인터 알고리즘
		while(true) {
			
			if(M==sum) {
				count++;
			}
			
			if(M<=sum) {
				sum-=arr[start++];
				continue;
			}
			
			if(end==N) {
				break;
			}
			
			if(sum<M) {
				sum+= arr[end++];
			}
			
		}
		
		System.out.println(count);	
	}
	
}