全网唯一递归法:
cpp
vector<vector<int>> generate(int numRows) {
vector<int> v;
vector<vector<int>>vn;
if (numRows == 1)
{
v.push_back(1);
vn.push_back(v);
v.clear();
return vn;//递归记得return
}
if (numRows == 2)
{
v.push_back(1);
vn.push_back(v);
v.clear();
v.push_back(1);
v.push_back(1);
vn.push_back(v);
v.clear();
return vn;//递归记得return
}
else
{
vn = generate(numRows - 1);//递归精髓
v = vn[numRows - 2];
vector<int> v2;
v2.resize(numRows, 1);
for (int i = 1; i < numRows - 1; i++)
{
v2[i] = v[i-1] + v[i];
}
vn.push_back(v2);
v.clear();
}
return vn;
}