更新时间:2022-10-03 13:48:39
118. Pascal's Triangle
Given numRows, generate the first numRows of Pascal's triangle.
For example, given numRows = 5,
Return
[ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ]
题目大意:
输入行数,输出如上图所示的数组。(杨辉三角)
思路:
用双vector来处理当前行和下一行。
代码如下:
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class Solution {
public :
vector<vector< int >> generate( int numRows) {
vector<vector< int >> result;
if (numRows == 0)
return result;
vector< int > curVec;
vector< int > nextVec;
for ( int i = 0;i < numRows; i++)
{
for ( int j = 0;j<=i;j++)
{
if (j == 0)
nextVec.push_back(1);
else
{
if (j >= curVec.size())
nextVec.push_back(curVec[j-1]);
else
nextVec.push_back(curVec[j] + curVec[j-1]);
}
}
result.push_back(nextVec);
curVec.swap(nextVec);
nextVec.clear();
}
return result;
}
};
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