1、可以遍历,但折半显然好一点;
2、!!!一定注意“非负”;
3、对象的写法{{}}
class Solution {
public:
vector<vector<int>> generate(int numRows) {
if(numRows == 0) return {};
if(numRows == 1) return {{1}};
vector<vector<int>> triangle(numRows);
triangle[0].resize(1);
triangle[0][0] = 1;
for(int i = 1; i < numRows; i++){
triangle[i].resize(i+1);
triangle[i][0] = 1;
triangle[i][i] = 1;
for(int j = 1; j < i; j++){
if(j >= i/2+1){
triangle[i][j] = triangle[i][i - j];
}else{
triangle[i][j] = triangle[i - 1][j - 1] + triangle[i - 1][j];
}
}
}
return triangle;
}
};