LeetCode Pascal's Triangle II

class Solution {
public:
    vector<int> getRow(int rowIndex) {
        int half = (rowIndex + 1) / 2;
        int len = half * 2  + !(rowIndex & 0x1);
        
        int* ra = new int[half + 1];
        int* rb = new int[half + 1];
        
        ra[0] = 1;
        rb[0] = 1;
        
        for (int i=1; i<=rowIndex; i++) {
            int h = (i + 1) / 2;
            int j = 1;
            for (; j<h; j++) {
                rb[j] = ra[j-1] + ra[j];
            }
            if (!(i & 0x1)) {
                rb[j] = ra[j-1] * 2;
            }
            int* t = ra;
            ra = rb;
            rb = t;
        }
        vector<int> res(len, 0);
        
        for (int i=0; i<half; i++) {
            res[i] = ra[i];
            res[len - i - 1] = ra[i];
        }
        if (!(rowIndex & 0x1)) res[half] = ra[half];
        return res;
    }
};