83차 2번번 문제풀이

Author: eric-hjh

live8/test83/문제2/황장현.js

@@ -0,0 +1,49 @@
+const input = require('fs')
+  .readFileSync(process.platform === 'linux' ? '/dev/stdin' : './input.txt')
+  .toString()
+  .trim()
+  .split('\n')
+  .map((el) => el.split(' ').map(Number));
+
+const LIMIT = 1299709;
+const isPrime = Array(LIMIT + 1).fill(true);
+isPrime[0] = isPrime[1] = false;
+const primes = [];
+
+for (let i = 2; i <= LIMIT; i++) {
+  if (isPrime[i]) {
+    primes.push(i);
+    for (let j = i * 2; j <= LIMIT; j += i) {
+      isPrime[j] = false;
+    }
+  }
+}
+
+function solution(input) {
+  const T = input[0];
+  const list = input.slice(1);
+  const result = [];
+
+  for (let numb of list) {
+    if (isPrime[numb]) {
+      result.push(0);
+      continue;
+    }
+
+    let left = 0,
+      right = primes.length - 1;
+    while (left < right) {
+      let mid = Math.floor((left + right) / 2);
+      if (primes[mid] >= numb) right = mid;
+      else left = mid + 1;
+    }
+
+    let prevPrime = primes[left - 1];
+    let nextPrime = primes[left];
+
+    result.push(nextPrime - prevPrime);
+  }
+  return result.join('\n');
+}
+
+console.log(solution(input));