[Sbeo-Joe] WEEK 01 solutions

contains-duplicate/Sbeo-Joe.cpp

@@ -0,0 +1,15 @@
+class Solution {
+public:
+    bool containsDuplicate(vector<int>& nums) {
+        set<int> s;
+
+        for(const auto& n : nums) {
+            auto iter = s.find(n);
+            if(iter != s.end()){
+                return true;
+            }
+            s.insert(n);
+        }
+        return false;
+    }
+};

house-robber/Sbeo-Joe.cpp

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    int map[101];
+    int rob(vector<int>& nums) {
+
+        memset(map, -1, sizeof(map));
+        int ret = -1;
+        for(int i = 0; i < nums.size(); i++){
+            ret = max(ret, solve(nums, i));
+        }
+        return ret;
+    }
+
+    int solve(vector<int>& nums, int here) {
+        if(here >= nums.size()) return 0;
+
+        int& ret = map[here];
+        if(ret != -1) return ret;
+        ret = nums[here];
+        for(int there = here + 2; there < nums.size(); there++){
+            ret = max(ret, solve(nums, there) + nums[here]);
+        }
+        return ret;
+    }
+
+};

longest-consecutive-sequence/Sbeo-Joe.cpp

@@ -0,0 +1,23 @@
+class Solution {
+public:
+    int longestConsecutive(vector<int>& nums) {
+        if(nums.size() == 0) return 0;
+        set<int> us{nums.begin(), nums.end()};
+        int ret = 1;
+        vector<int> vec(us.begin(), us.end());
+        int prevNum = vec[0];
+        int ret_candi = 1;
+        for(int i = 1; i < vec.size(); i++){
+            if(vec[i] - vec[i-1] == 1){
+                ret_candi++;
+                ret = max(ret, ret_candi);
+                continue;
+            } else {
+                ret_candi = 1;
+                continue;
+            }
+        }
+
+        return ret;
+    }
+};

top-k-frequent-elements/Sbeo-Joe.cpp

@@ -0,0 +1,22 @@
+class Solution {
+public:
+    vector<int> topKFrequent(vector<int>& nums, int k) {
+        // value, count
+        unordered_map<int, int> um;
+        for(auto& n : nums){
+            um[n]++;
+        }
+
+        //value, count
+        vector<std::pair<int, int>> vec(um.begin(), um.end());
+        sort(vec.begin(), vec.end(), 
+            [](const auto& a, const auto& b) { return a.second > b.second;});
+
+        vector<int> ret;
+        for(int i=0; i< k; i++){
+            ret.push_back(vec[i].first);
+        }
+
+        return ret;
+    }
+};

two-sum/Sbeo-Joe.cpp

@@ -0,0 +1,30 @@
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+
+        for(int i = 0; i < nums.size() - 1; i++){
+            for(int j = i + 1; j < nums.size(); j++){
+                if(nums[i] + nums[j] == target){
+                    return std::vector<int>{i, j};
+                }
+            }
+        }
+        return {};
+    }
+};
+
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        // value, index;
+        unordered_map<int, int> um;
+        for(int i = 0; i < nums.size(); i++){
+            int gap = target - nums[i]; 
+            if(um.count(gap)){
+                return {um[gap], i};
+            }
+            um[nums[i]] = i;
+        }
+        return {};
+    }
+};