巴斯卡三角形 Pascal triangle

 1 //++++++++++++++++++++++++++
 2  //      PascalTri.cpp
 3  //++++++++++++++++++++++++++
 4  
 5  ///#include header
 6  #include <iostream>
 7  #include <fstream>
 8  #include <iomanip> // setw(8)
 9  
10  ///Using & universal
11  using namespace std;
12  
13  ///main(i)
14  int main()
15  {
16      ///declare
17      int n;
18      int i, j;
19      unsigned tri[51][51];
20      
21      ///Prompt /Keyin
22      cout <<   " Please input size of Pascal triangle:   ";
23      cin >> n;
24      
25      ///within range
26      if (n<0 || n>=50) { cout <<"Only  0 ~ 50 !\n" << endl;  return 1;}
27      
28      ///tri[0][0] initial=1
29      tri[0][0] = 1;
30      
31      ///from 1st layer to Nth layer
32      for (i = 1; i <= n; i++)
33      {
34          ///fill "1" in row_edge ,  col_edge
35          tri[i][0] = tri[0][i] = 1;
36          
37          ///from 2nd layer to Nth layer
38          for (j = 1; j <= i-1; j++)//i=2 do 1st
39          {
40              ///layer sum
41              tri[i-j][j] = tri[i-j][j-1]+tri[i-j-1][j];
42              //i=2 j=1 1 1=      1    0 +        0  1
43              //i=3 j=1 2 1=      2    0 +        1  1
44              //i=3 j=2 1 2=      1    1 +        0  2
45              
46              ///+
47          }//end for
48          
49          ///+
50      }//end for
51      
52      ///from zero layer to Nth layer
53      for (i = 0; i <= n; i++)
54      {
55          ///left_blank decrease
56          for (j = 0; j < (n-i) ; j++)
57          {
58              ///left_blank= setw(8)/2
59              cout << "    " ;
60              
61              ///+
62          }//end for
63          
64          ///increase to layer end
65          for (j = 0; j <= i; j++)
66          {
67              ///Display setw(8)
68              cout << setw(8) << tri[i-j][j];
69              
70              ///+
71          }//end for
72          
73          ///CR/LF
74          cout << endl;
75          
76          ///+
77      }//end for
78      
79      ///main(o)
80      return 0 ;
81  } //main_end
82  

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