Node.js) 백준 2015번: 수들의 합 4

https://www.acmicpc.net/problem/2015

2015번: 수들의 합 4

 

const input = require('fs').readFileSync('./dev/stdin').toString().trim().split('\n');
const [N, K] = input[0].split(' ').map(Number);
const nums = input[1].split(' ');

const prefixSum = new Array(N);
let answer = 0;

let sum = 0;
const obj = {};
for (let i = 0; i < N; i++) {
	sum += Number(nums[i]);
	if (sum == K) answer++;
	prefixSum[i] = sum;
	if (obj[sum - K]) answer += obj[sum - K];
	if (!obj[sum]) obj[sum] = 1;
	else obj[sum]++;
}

console.log(answer);