Merge pull request #1777 from mumunuu/main

[mumunuu] WEEK 02 solutions

Author: SamTheKorean

climbing-stairs/mumunuu.java

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+// 70. Climbing Stairs https://leetcode.com/problems/climbing-stairs/description/
+class Solution {
+    public int climbStairs(int n) {
+
+
+        if (n <= 2) {
+            return n;
+        }
+
+        int a = 1;
+        int b = 2;
+
+        for (int i = 3; i <= n; i++) {
+            int temp = b;
+            b = a + b;
+            a = temp;
+        }
+
+        return b;
+
+
+    }
+}

product-of-array-except-self/mumunuu.java

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+class Solution {
+    public int[] productExceptSelf(int[] nums) {
+
+        // 원래는 그냥 다 곱해서 자기 빼고 나누면 되는데 나눗셈 하지 말라고 함
+
+        // 왼쪽 곱 구한다음에 오른쪽 곱으로 리턴하면 됨
+        int[] answer = new int[nums.length];
+
+        int left = 1;
+        answer[0] = left;
+
+        for (int i = 1; i < nums.length; i++) {
+            answer[i] = answer[i - 1] * nums[i - 1];
+        }
+
+        // 1 1 2 6
+
+        // 오른쪽 누적 곱
+
+        int right = 1;
+
+        for (int i = nums.length - 1; i >= 0; i--) {
+            answer[i] = answer[i] * right;
+            right *= nums[i];
+        }
+
+
+        return answer;
+
+    }
+}

valid-anagram/mumunuu.java

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+import java.util.Arrays;
+
+class Solution {
+    public boolean isAnagram(String s, String t) {
+
+        if (s.length() != t.length()) {
+            return false;
+        }
+
+        char[] a = s.toCharArray();
+        char[] b = t.toCharArray();
+
+        Arrays.sort(a);
+        Arrays.sort(b);
+
+        return Arrays.equals(a, b);
+
+    }
+}