silvergoni.builder()

https://leetcode.com/problems/robot-return-to-origin/ 1. 2022.01.27 시도 소요시간: 11분(3분 구상, 8분 코딩), 3분 class Solution { public boolean judgeCircle(String moves) { Map map = new HashMap(); map.put('U', 100000L); map.put('D', -100000L); map.put('L', 1L); map.put('R', -1L); long ret = 0; for(int i=0; i

https://leetcode.com/problems/middle-of-the-linked-list/ 1. 2022.01.24 시도 소요시간: 4분 class Solution { public ListNode middleNode(ListNode head) { if (head == null) { return null; } ListNode slow = head; ListNode fast = head.next; while(fast != null && fast.next != null) { slow = slow.next; fast = fast.next.next; } if (fast == null) { return slow; } return slow.next; } } 풀이 접근 과정 slow, fast로 하면 쉽게 ..

https://leetcode.com/problems/valid-palindrome/ 1. 2022.01.24 시도 소요시간: 7분(3분 구상, 4분 코딩, 공간복잡도O(n)), 11분(공간복잡도O(1)) // 공간복잡도: O(n) class Solution { public boolean isPalindrome(String s) { String filtered = ""; for(int x=0; x

https://leetcode.com/problems/reverse-string/ 1. 2022.01.24 시도 소요시간: 3분 class Solution { public void reverseString(char[] s) { for (int i=0; i

https://leetcode.com/problems/backspace-string-compare/ 1. 2022.01.22 시도 소요시간: 28분(구상 3분, 풀이 25분) class Solution { public boolean backspaceCompare(String s, String t) { char[] sa = new char[201]; char[] ta = new char[201]; int sl =convertAndGetLength(s, sa); int tl = convertAndGetLength(t, ta); if (sl == tl) { for (int x=0; x

https://leetcode.com/problems/backspace-string-compare/ 1. 2022.01.22 시도 소요시간: 28분(구상 3분, 풀이 25분) class Solution { public boolean backspaceCompare(String s, String t) { char[] sa = new char[201]; char[] ta = new char[201]; int sl =convertAndGetLength(s, sa); int tl = convertAndGetLength(t, ta); if (sl == tl) { for (int x=0; x

https://leetcode.com/problems/to-lower-case/ 1. 2022.01.17 시도 소요시간: 5분 class Solution { public String toLowerCase(String s) { String newWord = ""; for (int i=0; i= 'A' && s.charAt(i)

https://leetcode.com/problems/binary-search/ 1. 2022.01.17 시도 소요시간: 25분 class Solution { public int search(int[] nums, int target) { if (nums == null) { return -1; } return search(nums, target, 0, nums.length-1); } private int search(int[] nums, int target, int start, int end) { if (start > end ) { return -1; } int middle = (start + end)/2; if (target == nums[middle]) { return middle; } else if ..

https://leetcode.com/problems/path-sum/ 2. 2022/05/12 시도 소요시간: 8분(recursive-topdown), 8분(iterative-dfs) // recursive-topdown class Solution { boolean hasAnswer = false; int targetSum; public boolean hasPathSum(TreeNode root, int targetSum) { if (root == null) { return false; } this.targetSum = targetSum; recursive(root, 0); return hasAnswer; } private void recursive(TreeNode root, int sum) { if ..

https://leetcode.com/problems/reverse-integer/ 1. 2022.01.16 시도 소요시간: 10분 class Solution { public int reverse(int x) { if (-10 = 0) ? 1 : 1; int reversed = 0; while(x != 0) { int temp = (reversed * 10) + (x % 10); if (temp/10 != reversed) { //범위를 넘어버린 것 return 0; } reversed = temp; x = x/ 10; } return sign * reversed; } } 풀이 접근 과정 integer palindrome을 ..