Pascal ' s Triangle i,ii

The title comes from Leetcode

https://leetcode.com/problems/pascals-triangle/

Given numrows, generate the first numrows of Pascal ' s triangle.

For example, given numrows = 5,
Return

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

Class Solution {public:    vector<vector<int>> generate (int numrows) {        vector<vector<int> >res;        for (int i=0;i<numrows;i++)        {            Vector<int>vec (i+1,1);            if (i>1) for                (int j=1;j<i;j++)                    vec[j]=res[i-1][j-1]+res[i-1][j];            Res.push_back (VEC);            Vector<int> (). Swap (VEC);        }        return res;    }};

Pascal ' s Triangle IITotal Accepted: 42320 Total Submissions: 143760

Given an index K, return the kth row of the Pascal ' s triangle.

For example, given k = 3,
Return [1,3,3,1] .

Note:
Could optimize your algorithm to use only O(k) extra space?

There are memory requirements here although the first method can be AC but obviously not meet the requirements of

Class Solution {public:    vector<int> getRow (int rowIndex) {        vector<vector<int> >res;        for (int i=0;i<rowindex+1;i++)        {            Vector<int>vec (i+1,1);            if (i>1) for                (int j=1;j<i;j++)                    vec[j]=res[i-1][j-1]+res[i-1][j];            Res.push_back (VEC);            Vector<int> (). Swap (VEC);        }        return res[rowindex];}        ;

We have to redesign the algorithm. The first thought is that the Pascal triangle coefficients will be equal to the value of the N row I column equals (R N)
but

Class Solution {public:    vector<int> getRow (int rowIndex) {        vector<int>res (rowindex+1,1);        if (rowindex<2)        return res;       Long long nth=1;         for (int i=1;i<rowindex+1;i++)            nth*=i;         Long long rth=1,n_rth=nth;        for (int i=1;i<rowindex;i++)        {            n_rth/= (rowindex-i+1);            Res[i]=nth/rth/n_rth;                        Rth*= (i+1);        }          return res;    }};

The value used to store the two-item coefficients is easy to rowindex=24 at the time of the error. Finally, the correct method is to use the allocated space to calculate the specific description of the k=5.

Class Solution {public:    vector<int> getRow (int rowIndex) {        vector<int>res (rowindex+1,1);        if (rowindex<2)        return res;        int t1,t2;   for (int i=2;i<=rowindex;i++)    {        t1=res[0];        T2=RES[1];        for (int j=1;j<i+1;j++)        {            res[j]=t1+t2;            T1=t2;            T2=RES[J+1];        }        res[i]=1;    }        return res;    }};

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Pascal ' s Triangle i,ii