20190219

Author: HONGJICAI

cpp/148.SortList/mergeSort-52ms.cpp

@@ -0,0 +1,40 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode(int x) : val(x), next(NULL) {}
+ * };
+ */
+class Solution {
+    ListNode* separate(ListNode *h){
+        auto l=h,r=h;
+        ListNode* pre=nullptr;
+        while(r&&r->next){
+            r=r->next->next;
+            pre=l;
+            l=l->next;
+        }
+        if(pre)
+            pre->next=nullptr;
+        return l;
+    }
+public:
+    ListNode* sortList(ListNode* head) {
+        if(!head||!head->next)
+            return head;
+        auto rp=separate(head);
+        rp=sortList(rp);
+        auto lp=sortList(head);
+        auto h=ListNode(0);
+        auto p=&h;
+        while(lp&&rp){
+            auto &smallP=(lp->val<rp->val)?lp:rp;
+            p=p->next=smallP;
+            smallP=smallP->next;
+        }
+        for(auto cur=lp?lp:rp;cur;cur=cur->next)
+            p=p->next=cur;
+        return h.next;
+    }
+};

cpp/150.EvaluateReversePolishNotation/stack-20ms.cpp

@@ -0,0 +1,23 @@
+class Solution {
+public:
+    int evalRPN(vector<string>& tokens) {
+        stack<int> nums;
+        for(auto &s:tokens){
+            if(s[s.size()-1]>='0'&&s[s.size()-1]<='9')
+                nums.push(stoi(s));
+            else{
+                auto n2=nums.top();
+                nums.pop();
+                auto n1=nums.top();
+                nums.pop();
+                switch(s[0]){
+                    case '+':nums.push(n1+n2);break;
+                    case '-':nums.push(n1-n2);break;
+                    case '*':nums.push(n1*n2);break;
+                    case '/':nums.push(n1/n2);break;
+                }
+            }
+        }
+        return nums.top();
+    }
+};

cpp/152.MaximumProductSubarray/singleScan-8ms.cpp

@@ -0,0 +1,13 @@
+class Solution {
+public:
+    int maxProduct(vector<int>& nums) {
+        vector<int> maxPro(nums.size(),nums[0]),minPro(nums.size(),nums[0]);
+        auto ret=nums[0];
+        for(auto i=1;i<nums.size();++i){
+            maxPro[i]=max({nums[i],maxPro[i-1]*nums[i],minPro[i-1]*nums[i]});
+            minPro[i]=min({nums[i],maxPro[i-1]*nums[i],minPro[i-1]*nums[i]});
+            ret=max({ret,maxPro[i]});
+        }
+        return ret;
+    }
+};

cpp/152.MaximumProductSubarray/singleScanConstantSpace-8ms.cpp

@@ -0,0 +1,14 @@
+class Solution {
+public:
+    int maxProduct(vector<int>& nums) {
+        auto maxPro=nums[0],minPro=nums[0],ret=nums[0];
+        for(auto i=1;i<nums.size();++i){
+            auto curMaxPro=max({nums[i],nums[i]*maxPro,nums[i]*minPro});
+            auto curMinPro=min({nums[i],nums[i]*maxPro,nums[i]*minPro});
+            ret=max({ret,curMaxPro});
+            maxPro=curMaxPro;
+            minPro=curMinPro;
+        }
+        return ret;
+    }
+};