1.描述
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 you optimize your algorithm to use only O(k) extra space?
2.分析
3.代码
/**
* Return an array of size *returnSize.
* Note: The returned array must be malloced, assume caller calls free().
*/
int* getRow(int rowIndex, int* returnSize) {
if (rowIndex < 0) return NULL;
*returnSize = rowIndex + 1;
int* row = (int*)malloc(sizeof(int) * (*returnSize));
for (unsigned int i = 0; i< *returnSize; ++i)
row[i] = 1;
for (unsigned int i = 1; i<= rowIndex; ++i) {
int tmp = row[0];
for (unsigned int j = 1; j < i; ++j) {
int tmp2 = row[j];
row[j] = tmp + tmp2;
tmp = tmp2;
}
}
return row;
}
