Pascal's Triangle

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]

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解答

首先，很清楚可以知道其中的规律，[i][j]=[i-1][j]+[i-1][j-1];当然，这要除了边界全为1;直接计算

class Solution {public:    vector<vector<int>> generate(int numRows) {        vector<vector<int> > result(numRows, vector<int>());        for(int i=0; i<numRows; i++) {            for(int j=0; j<=i; j++) {              result[i].push_back(j == 0 ? 1 : j == i ? 1 : result[i-1][j-1] + result[i-1][j]);            }        }        return result;    }};