Pascal's Triangle--LeetCode

题目：

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]]

思路：第n层有n个数，而且第n层的首尾都是1，中间是上一层的两个的和

#include <iostream>#include <vector>#include <string>using namespace std;void  Pascaltriangle(int n){vector<vector<int> > result;int i,j;for(i=0;i<n;i++){vector<int> tmp;for(j=0;j<=i;j++){if(j==0 || j == i)tmp.push_back(1);elsetmp.push_back(result[i-1][j]+result[i-1][j-1]);}result.push_back(tmp);}for(i=0;i<result.size();i++){for(j=0;j<result[i].size();j++)cout<<result[i][j]<<" ";cout<<endl;}}int main(){Pascaltriangle(5);;return 0;}