题目:Given an index k, return the kth row of the Pascal's triangle.
For example, given k =
3,
Return [1,3,3,1]
.
思路:递推
思路很明确,一层一层递推,并且只需要设立一个数组,本题不难。只需要注意一个解题公式即可
代码:
class Solution1 { public://for more information,please email:j.z.feng@foxmail.com vector<int> getRow(int rowIndex) { vector<int> result(1,1); if(rowIndex==0){ return result; } for(int i=1;i<=rowIndex;i++){ vector<int>temp=result; for(int j=1;j<=i-1;j++){ result[j]=temp[j]+temp[j-1]; } result.push_back(1); temp.clear(); } return result; } };
class Solution2 { //此版本更加简洁 public:<pre name="code" class="cpp">//for more information,please email:j.z.feng@foxmail.comvector<int> getRow(int rowIndex) { vector<int> result(rowIndex+1,1); if(rowIndex<=1){ return result; } for(int i=2;i<=rowIndex;i++){ for(int j=i-1;j>=1;j--){ result[j]=result[j]+result[j-1]; } } return result; }};