Add C++ solutions for leetecode 1002 and 1005.

Author: yanglr

cpp-leetcode/leetcode1002-find-common-characters_hashmap.cpp

@@ -0,0 +1,48 @@
+#include<vector>
+#include<algorithm>
+#include<iostream>
+#include<cstring>
+using namespace std;
+
+class Solution {
+public:
+    vector<string> commonChars(vector<string>& words) {
+        vector<string> res;
+        int minDict[26]; // 统计每个字母的最小count
+        fill(minDict, minDict + 26, INT_MAX);     
+        for (int j = 0; j < words.size(); j++) // 将每一个单词进行哈希化, 然后分别算出每个字母的最小count
+        {
+            string curWord = words[j];
+            vector<int> curDict(26, 0); // 26个字母
+            for (auto& ch : curWord)
+                curDict[ch - 'a']++;
+            for (int i = 0; i < 26; i++)
+                minDict[i] = min(minDict[i], curDict[i]);         
+        } 
+        for (int i = 0; i < 26; i++)
+        {
+            int curCount = minDict[i];
+            if (curCount >= 1)
+            {
+                auto ch = i + 'a';
+                string str;
+                str.push_back(ch);
+                for (int i = 0; i < curCount; i++)
+                    res.push_back(str);
+            }            
+        }        
+        return res;
+    }
+};
+
+// Test
+int main()
+{
+    Solution sol;
+    vector<string> words = {"cool", "lock", "cook"};
+    auto res = sol.commonChars(words);
+    for (auto str : res)
+        cout << str << endl;
+
+    return 0;
+}

cpp-leetcode/leetcode1005-maximize-sum-of-array-after-k-negations_classification.cpp

@@ -0,0 +1,73 @@
+#include<vector>
+#include<algorithm>
+#include<iostream>
+#include<numeric>
+using namespace std;
+
+class Solution {
+public:
+    int largestSumAfterKNegations(vector<int>& nums, int k) {
+        int m = 0; // 负数的个数
+        for (auto& num : nums)
+            if (num < 0) m++;
+        auto sum = accumulate(nums.begin(), nums.end(), 0);            
+        if (m == 0 && k % 2 == 0)
+            return sum;
+        else if (m == 0 && k % 2 == 1)
+        {
+            auto it = min_element(nums.begin(), nums.end());
+            return sum - 2*(*it);
+        }  
+        else if (m > 0 && m >= k)
+        {
+            sort(nums.begin(), nums.end());
+            int sum1 = 0;
+            for (int i = 0; i < nums.size(); i++)
+            {
+                if (i <= k-1) /* 题意: k >= 1, k-1不会成负数 */
+                    sum1 += -nums[i]; 
+                else sum1 += nums[i];                
+            }                       
+            return sum1;
+        }
+        else if (m > 0 && m < k)
+        {
+            if ((k - m) % 2 == 0)
+            {
+                int sum1 = 0;
+                for (int i = 0; i < nums.size(); i++)
+                {
+                    if (nums[i] < 0) 
+                        sum1 += -nums[i]; 
+                    else sum1 += nums[i];                
+                }  
+                return sum1;  
+            }
+            else {
+                int sum1 = 0;
+                for (int i = 0; i < nums.size(); i++)
+                {
+                    if (nums[i] < 0) 
+                       nums[i] = -nums[i];    
+                    sum1 += nums[i];            
+                }                  
+                sort(nums.begin(), nums.end());
+                auto it = min_element(nums.begin(), nums.end());
+                return sum1 - 2*(*it);                
+            }
+        }
+        return 0;      
+    }
+};
+
+// Test
+int main()
+{
+    Solution sol;
+    vector<int> nums = {5, 6, 9, -3, 3};
+    int k = 2;
+    auto res = sol.largestSumAfterKNegations(nums, k);
+    cout << res << endl;
+
+    return 0;
+}