leetcode others...

int maxProfit(vector<int> &prices) {//Best Time to Buy and Sell Stock          if (prices.size() == 0)        return 0;    int low = prices[0];    int profit = 0;    for (int i = 1; i < prices.size(); ++i)    {        low = min(prices[i], low);        profit = max(profit, prices[i] - low);    }    return profit;    }public int longestValidParentheses(String s) {//Longest Valid Parentheses  )()())    int maxLen = 0, last = -1;    Stack<Integer> lefts = new Stack<Integer>();    for (int i=0; i<s.length(); ++i) {        if (s.charAt(i)=='(') {            lefts.push(i);        } else {            if (lefts.isEmpty()) {                // no matching left                last = i;            } else {                // find a matching pair                lefts.pop();                if (lefts.isEmpty()) {                    maxLen = Math.max(maxLen, i-last);                } else {                    maxLen = Math.max(maxLen, i-lefts.peek());                }            }        }    }    return maxLen;}vector<int> twoSum(vector<int> &numbers, int target) {//two sum 4,4,5,3,2 target=8        vector<int> result;if(numbers.size()==0) return result;map<int,set<int>> numMap;for(int i=0;i<numbers.size();i++){numMap[numbers[i]].insert(i);}map<int,set<int>>::iterator it;set<int>::iterator setIt;for(int i=0;i<numbers.size();i++){it=numMap.find(target-numbers[i]);if(it!=numMap.end()){for(setIt=it->second.begin();setIt!=it->second.end();setIt++){if((*setIt)>i){result.push_back(i+1);//index+1 result.push_back(*setIt+1);//index+1return result;}}}}return result;}vector<vector<int> > threeSum(vector<int> &num) {//3 sum         vector<vector<int>> result;        int n=num.size();        if(n<=2) return result;        sort(num.begin(),num.end());        vector<int> resultItem(3);        for(int i=0;i<=n-3;i++)        {            if(i>0&&num[i]==num[i-1]) continue;            int target=-num[i];            int j=i+1;            int k=n-1;            while(j<k)            {                if(num[j]+num[k]==target)                {                    resultItem[0]=num[i];                    resultItem[1]=num[j];                    resultItem[2]=num[k];                    result.push_back(resultItem);                    j++;                    k--;                    while(j<k&&num[j]==num[j-1])                        j++;                }                else if(num[j]+num[k]>target)                {                    k--;                }                else                {                    j++;                }            }        }        return result;    }void merge(int A[], int m, int B[], int n) {//Merge Sorted Array        int i=m-1;int j=n-1;int k=m+n-1;        while(i>=0&&j>=0)        {            A[k--]=A[i]>B[j]?A[i--]:B[j--];        }        while(j>=0)        {            A[k--]=B[j--];        }        return ;    }int removeElement(int A[], int n, int elem) {//Remove Elementint len = 0;for (int i = 0; i < n; i++){   if (A[i] != elem)A[len++] = A[i];}return len;}//Merge Intervalsclass myComp {  public:    bool operator()(const Interval &i1, const Interval &i2) {      return i1.start < i2.start;    }};class Solution {public:    vector<Interval> merge(vector<Interval> &intervals) {        vector<Interval> result;        int n=intervals.size();        if(n==0) return result;        sort(intervals.begin(),intervals.end(),myComp());        result.push_back(intervals[0]);        for(int i=1;i<n;i++)        {            if(intervals[i].start>result.back().end)            {                result.push_back(intervals[i]);            }            else            {                result.back().end=max(result.back().end,intervals[i].end);            }        }        return result;    }};//Insert Interval vector<Interval> insert(vector<Interval> &intervals, Interval newInterval) {        // Start typing your C/C++ solution below        // DO NOT write int main() function            vector<Interval> result;            if(intervals.size()==0)             {                result.push_back(newInterval);                return result;            }            int i=0;            while(i<intervals.size()&&intervals[i].end<newInterval.start)            {                result.push_back(intervals[i++]);            }            result.push_back(newInterval);            while(i<intervals.size())            {                if(intervals[i].start<=result.back().end)                {                    result.back().start=min(result.back().start,intervals[i].start);                    result.back().end=max(result.back().end,intervals[i].end);                    i++;                }                else                {                    result.push_back(intervals[i++]);                   }            }            return result;}//Merge Two Sorted ListsListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(!l1) return l2;        if(!l2) return l1;        ListNode* head=NULL;        if(l1->val>l2->val)        {            head=l1;            l1=l1->next;        }        else        {            head=l2;            l2=l2->next;        }        ListNode* p=head;        while(l1&&l2)        {            if(l1->val>l2->val)            {                p->next=l1;                l1=l1->next;            }            else            {                p->next=l2;                l2=l2->next;            }            p=p->next;        }        while(l1)        {            p->next=l1;            l1=l1->next;            p=p->next;        }        while(l2)        {            p->next=l2;            l2=l2->next;            p=p->next;        }        return head;}//a recursive solution  Merge Two Sorted ListsListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {        // Start typing your C/C++ solution below        // DO NOT write int main() functionif(!l1) return l2;if(!l2) return l1;ListNode* head=NULL;if(l1->val>l2->val){head=l1;head->next=mergeTwoLists(l1->next,l2);}else{head=l2;head->next=mergeTwoLists(l1,l2->next);}return head;}//Remove Nth Node From End of ListListNode *removeNthFromEnd(ListNode *head, int n) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(!head||n<=0) return head;                int len=0;        int first=head;        int second=NULL;        while(first)        {            len++;            if(len==n+1)            {                second=head;            }            else if(len>n+1)            {                second=second->next;            }            first=first->next;        }                if(len==n)         {            ListNode* temp=head;            head=head->next;            free(temp);        }        else        {            ListNode* temp=second->next;            second->next=temp->next;            free(temp);        }        return head;    }//Add Two Numbers  (2 -> 4 -> 3) + (5 -> 6 -> 4) ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(!l1) return l2;        if(!l2) return l1;                int carry=0;        int num1=0;        int num2=0;        ListNode* head=NULL;        ListNode* p=NULL;        while(l1||l2||carry!=0)        {            num1=0;            num2=0;            if(l1)            {                num1=l1->val;                l1=l1->next;            }            if(l2)            {                num2=l2->val;                l2=l2->next;            }            int sum=num1+num2+carry;            carry=sum/10;            sum%=10;            ListNode* node=new ListNode(sum);            if(!head)            {                head=node;                p=node;            }            else            {                p->next=node;                p=p->next;            }          }        return head;    }//Swap Nodes in PairsListNode *swapPairs(ListNode *head) {if(!head||!head->next) return head;ListNode* second=head;ListNode* first=head->next;ListNode* next=first->next;first->next=second;second->next=swapPairs(next);return first;}//Partition List ListNode *partition(ListNode *head, int x) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(!head) return head;        ListNode* p=head;        ListNode* head1=NULL;        ListNode* tail1=NULL;        ListNode* head2=NULL;        ListNode* tail2=NULL;        while(p)        {            if(p->val<x)            {                if(!head1)                {                    head1=p;                    tail1=p;                }                else                {                    tail1->next=p;                    tail1=tail1->next;                }            }            else            {                if(!head2)                {                    head2=p;                    tail2=p;                }                else                {                    tail2->next=p;                    tail2=tail2->next;                }            }            p=p->next;        }    if(tail1) tail1->next=NULL;if(tail2) tail2->next=NULL;        if(head1)        {            tail1->next=head2;            return head1;        }        else        {            return head2;        }    }int lengthOfLastWord(const char *s) {//Length of Last Word        // Start typing your C/C++ solution below        // DO NOT write int main() function        if(!s) return 0;        int lastlen=0;        int currentlen=0;        while(*s)        {            if(*s==' ')            {                if(currentlen!=0)                {                    lastlen=currentlen;                }                currentlen=0;            }            else            {                currentlen++;            }            s++;        }        if(currentlen!=0)        {            lastlen=currentlen;        }        return lastlen;    }