[week 10] 주간 결산_전언석

언석/week10/1.js

@@ -0,0 +1,12 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12937
+// 짝수와 홀수
+
+function solution(num) {
+  return num % 2 === 0 ? 'Even' : 'Odd';
+}
+
+// 다른 사람 풀이
+
+function evenOrOdd(num) {
+  return num % 2 ? "Odd" : "Even"
+}

언석/week10/2.js

@@ -0,0 +1,8 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12910
+// 나누어 떨어지는 숫자 배열
+
+function solution(arr, divisor) {
+  const result = arr.filter((num) => !(num % divisor));
+
+  return result.length ? result.sort((a, b) => a - b) : [-1];
+}

언석/week10/3.js

@@ -0,0 +1,8 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12919
+// 서울에서 김서방 찾기
+
+function solution(seoul) {
+  return `김서방은 ${seoul.indexOf('Kim')}에 있다`
+}
+
+console.log(solution(['Jane', 'Kim']));

언석/week10/4.js

@@ -0,0 +1,8 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12933
+// 정수 내림차순으로 배치하기
+
+function solution(n) {
+  const arr = String(n).split('');
+
+  return Number(arr.sort().reverse().join(''));
+}

언석/week8/1.js

@@ -0,0 +1,15 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12935
+// 제일 작은 수 제거하기
+
+function solution(arr) {
+  const minIdx = arr.indexOf(Math.min(...arr));
+  console.log(minIdx);
+
+  arr.splice(minIdx, 1)
+
+  if (arr.length === 0) {
+    return [-1]
+  }
+
+  return arr;
+}

언석/week8/2.js

@@ -0,0 +1,38 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12903
+// 가운데 글자 가져오기
+
+function solution(s) {
+  const strLen = s.length;
+
+  const midIdx = Math.floor(strLen / 2);
+
+  if (strLen % 2 !== 0) return s[midIdx];
+  if (strLen % 2 === 0) return s[midIdx - 1] + s[midIdx];
+
+  return midIdx;
+}
+
+// 다른 사람 풀이
+
+function solution2(s) {
+    return s.substr(Math.ceil(s.length / 2) - 1, s.length % 2 === 0 ? 2 : 1);
+}
+
+/** 
+ * substr()
+ * 사용을 권장하진 않는다고 한다.
+ * 
+ * substr(start)
+ * substr(start, length)
+ * 
+ * return vale
+ * 해당 부분의 새로운 string
+ * 
+ * const str = 'Mozilla';
+ * 
+ * console.log(str.substr(1, 2));
+ * // Expected output: "oz"
+ * 
+ * console.log(str.substr(2));
+ * // Expected output: "zilla"
+ */

언석/week8/3.js

@@ -0,0 +1,28 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12917
+// 문자열 내림차순으로 배치하기
+
+function solution(s) {
+  return (Array(...s).sort().reverse().join(''));
+}
+
+// 다른 풀이
+function solution2(s) {
+  return s
+    .split("")
+    .sort()
+    .reverse()
+    .join("");
+}
+
+/**
+ * obj.sort().reverse();
+ * vs
+ * obj.sort((a, b) => (a > b ? -1 : 1))
+ * vs
+ * obj.sort((a, b) => b.localeCompare(a))
+ * 
+ * winner is obj.sort().reverse()
+ * 
+ * ref
+ * https://stackoverflow.com/questions/52030110/sorting-strings-in-descending-order-in-javascript-most-efficiently
+ */

언석/week9/1.js

@@ -0,0 +1,17 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12948
+// 핸드폰 번호 가리기
+
+function solution(phone_number) {
+  return '*'.repeat(phone_number.length - 4) + phone_number.slice(phone_number.length - 4);
+}
+
+// 다른 사람 풀이1
+function hide_numbers(s){
+  return s.replace(/\d(?=\d{4})/g, "*");
+}
+
+// 다른 사람 풀이2
+function hide_numbers(s){
+  var result = "*".repeat(s.length - 4) + s.slice(-4);
+  return result;
+}

언석/week9/2.js

@@ -0,0 +1,24 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12912
+// 두 정수 사이의 합
+
+function solution(a, b) {
+  let sum = 0;
+  if (a < b) {
+    for (let i = a; i <= b; i++) {
+      sum += i;
+    }
+  } else {
+    for (let i = b; i <= a; i++) {
+      sum += i;
+    }
+  }
+
+  return sum;
+}
+
+// 다른 사람 풀이
+function adder(a, b, s = 0){
+  for (var i = Math.min(a, b); i <= Math.max(a, b); i++) s += i;
+
+  return s;
+}

언석/week9/3.js

@@ -0,0 +1,12 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/86051
+// 없는 숫자 더하기
+
+function solution(numbers) {
+  let answer = 0;
+
+  for (let i = 0; i < 10; i++) {
+    if (!numbers.includes(i)) answer += i;
+  }
+
+  return answer;
+}

언석/week9/4.js

@@ -0,0 +1,8 @@
+// https://school.programmers.co.kr/learn/courses/30/lessons/12931
+// 자릿수 더하기
+
+function solution(n) {
+    let answer = String(n).split('').reduce((acc, cur) => +acc + +cur, 0);
+
+    return answer;
+}