[ys-han00] WEEK 02 solutions

climbing-stairs/ys-han00.cpp

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    int climbStairs(int n) {
+        vector<int> fibo(46, 0);
+
+        fibo[1] = 1;
+        fibo[2] = 2;
+
+        if(n <= 2)
+            return fibo[n];
+
+        for(int i = 3; i <= n; i++)
+            fibo[i] = fibo[i - 1] + fibo[i - 2];
+
+        return fibo[n];
+    }
+};
+

product-of-array-except-self/ys-han00.cpp

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+class Solution {
+public:
+    vector<int> productExceptSelf(vector<int>& nums) {
+        int mul = 1, zero_cnt = 0;
+
+        for(int i = 0; i < nums.size(); i++) {
+            if(nums[i] != 0)
+                mul *= nums[i];
+            else
+                zero_cnt++;
+        }
+
+        vector<int> ans = vector<int>(nums.size(), 0);
+
+        if(zero_cnt == 1) {
+            for(int i = 0; i < nums.size(); i++) {
+                if(nums[i] == 0) {
+                    ans[i] = mul;
+                    break;
+                }
+            }
+        } else if(zero_cnt == 0) {
+            for(int i = 0; i < nums.size(); i++)
+                ans[i] = mul / nums[i];
+        }
+
+        return ans;
+    }
+};
+

valid-anagram/ys-han00.cpp

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+// class Solution {
+// public:
+//     bool isAnagram(string s, string t) {
+//         map<char, int> counter;
+
+//         for(int i = 0; i < s.size(); i++)
+//             counter[s[i] - 'a']++;
+//         for(int i = 0; i < t.size(); i++)
+//             counter[t[i] - 'a']--;
+
+//         for(auto const& iter : counter)
+//             if(iter.second != 0)
+//                 return false;
+
+//         return true;
+//     }
+// };
+
+class Solution {
+public:
+    bool isAnagram(string s, string t) {
+        vector<int> counter(26, 0);
+
+        for(int i = 0; i < s.size(); i++)
+            counter[s[i] - 'a']++;
+        for(int i = 0; i < t.size(); i++)
+            counter[t[i] - 'a']--;
+
+        for(int i = 0; i < 26; i++)
+            if(counter[i] != 0)
+                return false;
+
+        return true;
+    }
+};
+