[sonshn] WEEK 02 Solutions

climbing-stairs/sonshn.java

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+/**
+ * dp[i] = dp[i - 1] + dp[i - 2]
+ */
+class Solution {
+    public int climbStairs(int n) {
+        if (n <= 2) {
+            return n;
+        }
+
+        int[] dp = new int[n + 1];
+        dp[1] = 1;
+        dp[2] = 2;
+
+        for (int i = 3; i <= n; i++) {
+            dp[i] = dp[i - 1] + dp[i - 2];
+        }
+
+        return dp[n];
+    }
+}

valid-anagram/sonshn.java

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+import java.util.*;
+
+/**
+ * String to char array, sort, and compare
+ * 
+ * 시간 복잡도: O(nlogn)
+ * 공간 복잡도: O(n)
+ */
+class Solution {
+    public boolean isAnagram(String s, String t) {
+        char[] sArray = s.toCharArray();
+        char[] tArray = t.toCharArray();
+
+        Arrays.sort(sArray);
+        Arrays.sort(tArray);
+
+        return Arrays.equals(sArray, tArray);
+    }
+}