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Given numRows, generate the first numRows of Pascal's triangle.
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For example, given numRows = 5,
Return
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[
? ? ?[1],
? ? [1,1],
? ?[1,2,1],
? [1,3,3,1],
?[1,4,6,4,1]
]?
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问题描述：给定一个整数numRows，生成Pascal三角形的前numRows行。
将该三角形的左边对齐，就能够发现，tri[i][j] = tri[i-1][j-1] + tri[i-1][j]。
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class Solution {
public:
vector > generate(int numRows) {
// Note: The Solution object is instantiated only once and is reused by each test case.
if(numRows == 0)
return vector >(0);
vector > ivec;
int i = 0, j = 0;
for(i = 0; i < numRows; i++) {
vector vec;
for(j = 0; j < i+1; j++) {
if(j == 0 || j == i)
vec.push_back(1);
else
vec.push_back(ivec[i-1][j-1] + ivec[i-1][j]);
}
ivec.push_back(vec);
}
return ivec;
}
};
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