118 - Pascal's Triangle

Given numRows, generate the first numRows of Pascal's triangle.

For example, given numRows = 5,

Return

[     [1],    [1,1],   [1,2,1],  [1,3,3,1], [1,4,6,4,1]]

Solution: 

class Solution {public:    vector
     
      
       > generate(int numRows) {        vector
       
        
         > ret;        if(numRows==0)return ret;        vector
         
           vec(1,1);        ret.push_back(vec);        int i=1;        while(i
         
        
       
      
     

 

119 - Pascal's Triangle II

Given an index k, return the kth row of the Pascal's triangle.

For example, given k = 3,

Return [1,3,3,1].

Note:

Could you optimize your algorithm to use only O(k) extra space?

Solution：

class Solution {public:    vector
     
       getRow(int rowIndex) {        vector
      
        vec(1,1);        vector
       
        
         > ret;            ret.push_back(vec);        int i=1;        while(i<=rowIndex){            vec.clear();            vec.push_back(1);            for(int j=1;j