No.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]
]
解法：其实很简单，想清楚就好，找好规律！！
1 #include "stdafx.h"
2 #include <string>
3 #include <vector>
4 #include <iostream>
5 #include <algorithm>
6 using namespace std;
7
8 class Solution
9 {
10 public:
11 vector<vector<int>> generate(int numRows)
12 {//生成帕斯卡三角形
13 //找规律
14 vector<vector<int>> res;
15 if(numRows<=0)
16 return res;
17 vector<int> front;
18 for(int i=0; i<numRows; i++)
19 {
20 vector<int> tmp;
21 for(int j=0; j<i+1; j++)
22 {
23 if(j==0 || j==i)
24 tmp.push_back(1);
25 else
26 {
27 tmp.push_back(front[j]+front[j-1]);//又是i、j傻傻分不清楚!!!
28 }
29 }
30 front = tmp;
31 res.push_back(tmp);
32 }
33 return res;
34 }
35 };
36
37 int main()
38 {
39 Solution sol;
40 int numRows;
41 vector<vector<int>> res;
42 while(cin >> numRows)
43 {
44 cout << numRows<<" : "<<endl;
45 res = sol.generate(numRows);
46 for(const auto &i : res)
47 {
48 for(const auto &j : i)
49 cout << j << " ";
50 cout << endl;
51 }
52 cout <<"--------------"<<endl;
53 }
54 }
