给定行号，输出如下所示Pascal Triangle（杨辉三角）
For example, given numRows = 5,
Return
[
[1],
[1,1],
[1,2,1],
[1,3,3,1],
[1,4,6,4,1]
]
class Solution {
public:
vector<int> fun116(vector<int> perm)
{
vector<int> tmp;
tmp.push_back(1);
for (int i = 0; i < perm.size() - 1; i++)
{
tmp.push_back(perm[i] + perm[i + 1]);
}
tmp.push_back(1);
return tmp;
}
vector<vector<int> > generate(int numRows)
{
vector<vector<int> > ans;
if (numRows == 0) return ans;
vector<int> perm(1,1);
while(numRows-- > 0)
{
ans.push_back(perm);
perm = fun116(perm);
}
return ans;
}
};
也可以这样：
class Solution { public: vector<vector<int> > generate(int numRows) { // Note: The Solution object is instantiated only once and is reused by each test case. vector<vector<int> > res; if(numRows == 0) return res; for(int i = 1; i <= numRows; i++) { vector<int> onelevel; onelevel.clear(); onelevel.push_back(1); for(int j = 1; j < i; j++) { onelevel.push_back(res[i-2][j-1] + (j < i-1 ? res[i-2][j] : 0)); } res.push_back(onelevel); } return res; } };
原文：http://www.cnblogs.com/higerzhang/p/4133855.html