题目描述:
在杨辉三角中,每个数是它左上方和右上方的数的和。
示例:
输入: 5 输出: [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ]
我提交的代码:
class Solution {
public:
vector<vector<int>> generate(int numRows) {
vector<int> preVec;
vector<vector<int>> result;
int i;
for (i = 1; i <= numRows; ++i){
vector<int> tempVec;
if(1 == i){
tempVec.push_back(1);
}
else{
int preSize = preVec.size();
tempVec.push_back(1);
for (int j = 0; j < preSize - 1; ++j){
int addVal = preVec[j] + preVec[j+1];
tempVec.push_back(addVal);
}
tempVec.push_back(1);
}
result.push_back(tempVec);
preVec = tempVec;
}
return result;
}
};