[hsskey] Week 02 Solutions

climbing-stairs/hsskey.js

@@ -0,0 +1,19 @@
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var climbStairs = function(n) {
+    if(n <= 2) {
+        return n
+    }
+
+    let dp = new Array(n + 1)
+    dp[1] = 1
+    dp[2] = 2
+
+    for(let i = 3; i <= n; i++) {
+        dp[i] = dp[i - 1] + dp[i - 2]
+    }
+
+    return dp[n]
+};

product-of-array-except-self/hsskey.js

@@ -0,0 +1,23 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+var productExceptSelf = function(nums) {
+    const n = nums.length
+    const result = Array(nums.length)
+
+    let left = 1
+
+    for(let i = 0; i < n; i++) {
+        result[i] = left
+        left *= nums[i]
+    }
+
+    let right = 1
+    for(let i = n - 1; i >= 0; i--) {
+        result[i] *= right
+        right *= nums[i]
+    }
+
+    return result
+};

valid-anagram/hsskey.js

@@ -0,0 +1,38 @@
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {boolean}
+ */
+var isAnagram = function(s, t) {
+    if(s.length !== t.length) {
+        return false
+    }
+    const sMap = new Map()
+    const tMap = new Map()
+
+    for(let i = 0; i < s.length; i++) {
+        if(sMap.has(s[i])) {
+            const prevVal = sMap.get(s[i])
+            sMap.set(s[i], prevVal + 1)
+        } else {
+            sMap.set(s[i], 1)
+        }
+    }
+
+    for(let i = 0; i < t.length; i++) {
+        if(tMap.has(t[i])) {
+            const prevVal = tMap.get(t[i])
+            tMap.set(t[i], prevVal + 1)
+        } else {
+            tMap.set(t[i], 1)
+        }
+    }
+
+    for(const[char, count] of sMap) {
+        if(!tMap.has(char) || tMap.get(char) !== count) {
+            return false
+        }
+    }
+
+    return true
+};