"Leetcode-Interview algorithm classic-java Implementation" "118-pascal ' s Triangle (Pascal Triangle)"

"118-pascal ' s Triangle (Pascal triangle (Yang Hui triangle))""leetcode-Interview algorithm classic-java Implementation" "All topics Directory Index"Original Question

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]]

Main Topic

Given a positive integer n, the n-layer Pascal triangle is obtained.

Thinking of solving problems

For any n>0, there are
F (1, N) =1, (n>0)
F (1, 2) =1, (n=2)
F (i,j) = f (i-1, j-1) +f (i, j-1), i>2,j>2

Code Implementation

Algorithm implementation class

 PublicClass Solution { Public List<List<Integer>>Generate (int numrows) {if(NumRows< 0) {return NULL; }List<List<Integer>> List = NewArrayList<>();if(NumRows>= 1) {List<Integer> Data = NewArrayList<>();Data.Add1);List.AddData); }if(NumRows>= 2) {List<Integer> Data = NewArrayList<>();Data.Add1);Data.Add1);List.AddData); }if(NumRows>=3) {for (int i= 3; I<=NumRows; I++) {List<Integer> Data = NewArrayList<>();List<Integer>Prev= List.Get (i- 2);Data.Add1); for (Int J= 2; J<=I-1; J++) {Data.Add (prev.Get (J- 2)+Prev.Get (J- 1)); }Data.Add1);List.AddData); }        }return List; }}

Evaluation Results

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"Leetcode-Interview algorithm classic-java Implementation" "118-pascal ' s Triangle (Pascal Triangle)"