OJ Practice 28--t118 Pascal's Triangle

Print Yang Hui triangle:

[
[1],
[All],
[1,2,1],
[1,3,3,1],
[1,4,6,4,1]
]

Enter the number of lines printed and return the vector<vector<int> > type.

Ideas

1. My idea is to allocate vector space first, use resize, and then use subscript to access [i].

2. The other person's idea, each line is a new vector<int> cur, assigns the value after push_back to the RET.

"Other Codes"

vector<vector<int> > Generate (intnumrows) {        intI, J;         for(i=0; i<numrows; i++) {vector<int>cur; if(i==0) Cur.push_back (1);            Else{             for(j=0; j<=i; J + +)            {                if(j==0|| j==i) Cur.push_back (1); Else{                    intans=ret[i-1][j-1]+ret[i-1][j];                Cur.push_back (ANS); }}} ret.push_back (cur); }        returnret; }

"My Code"

vector<vector<int> > Generate (intnumrows) {Vector<vector<int> >ret;
if (numrows==0)
return ret; intI, J;    Ret.resize (NumRows); ret[0].push_back (1);  for(i=1; i<numrows; i++) {ret[i].resize (i+1); ret[i][0]=1; Ret[i][i]=1;  for(j=1; j<i; J + +) {Ret[i][j]=ret[i-1][j-1]+ret[i-1][j]; }    }    returnret;}

Evaluation

It always fails at first, showing that the last Test executed was {0},

Add if (numrows==0) return ret; this sentence is OK, should consider the illegal situation, so that the return of RET is an empty vector?!

OJ Practice 28--t118 Pascal's Triangle