Subarray Sum Equals K
JavaScript
Medium
3 views
Problem Description
Given n, k and an array. Count how many subarrays have sum exactly k.
Input Format
Line1: n k. Line2: n integers.
Output Format
One integer count.
Official Solution
const fs=require('fs');const a=fs.readFileSync(0,'utf8').trim().split(/\\s+/);if(!a[0])process.exit(0);let i=0;const n=Number(a[i++]);const k=BigInt(a[i++]);let pref=0n;const map=new Map();map.set('0',1);let ans=0n;for(let j=0;j<n;j++){pref+=BigInt(a[i++]);const need=(pref-k).toString();ans+=BigInt(map.get(need)||0);const key=pref.toString();map.set(key,(map.get(key)||0)+1);}process.stdout.write(ans.toString());
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