07
05/2015
[LeetCode] Pascal's Triangle
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] ]
解题思路：
模拟方法，逐层实现即可。
class Solution {
public:
vector<vector<int>> generate(int numRows) {
vector<vector<int>> result;
if(numRows==0){
return result;
}
result.push_back(vector<int>({1}));
for(int i=1; i < numRows; i++){
result.push_back(vector<int>());
for(int j=0; j<=i; j++){
if(j==0 || j==i){
result[i].push_back(1);
}else{
result[i].push_back(result[i-1][j-1] + result[i-1][j]);
}
}
}
return result;
}
};二次刷题（2015-08-04）
class Solution {
public:
vector<vector<int>> generate(int numRows) {
vector<vector<int>> result;
if(numRows<=0){
return result;
}
result.push_back(vector<int>({1}));
for(int i=1; i<numRows; i++){
vector<int> item({1});
for(int j=1; j<i; j++){
item.push_back(result[i-1][j-1] + result[i-1][j]);
}
item.push_back(1);
result.push_back(item);
}
return result;
}
};转载请注明：康瑞部落 » [LeetCode] Pascal's Triangle
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