Submission #68126858

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Source Code Expand

import { readFileSync } from 'fs';
const stdin = readFileSync('/dev/stdin', 'utf8');
const lines = stdin.trim().split('\n');

const n = Number(lines.shift());
const a = lines.shift().split(' ').map(Number);

// j - i = a[i] + a[j]
// => a[i] + i = j - a[j]

const freq = new Map<number, number>();
let ans = 0;
for (let i = 0; i < n; i++) {
  ans += freq.get(i - a[i]) ?? 0;
  const k = a[i] + i;
  freq.set(k, (freq.get(k) ?? 0) + 1);
}

console.log(ans);

Submission Info

Compile Error

Judge Result