[Leetcode]-Pascal's Triangle II

標籤：leetcode

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?

Hide Tags : Array
題目：返回帕斯卡三角形第K行的元素，頂點1即為第0行。
注意：只能使用O(k)額外空間

/** * Return an array of size *returnSize. * Note: The returned array must be malloced, assume caller calls free(). */int* getRow(int rowIndex, int* returnSize) {    *returnSize = rowIndex+1;    if(0 > rowIndex) return 0;    int* r = (int*)malloc(sizeof(int)*(rowIndex+1));    if(0 == rowIndex)    {        r[0] = 1;        return r;    }    int i = 0 ,j = 0;    int m=0,n=0;    for(i=1;i<=rowIndex;i++)    {        r[0] = r[i] = 1;        m = r[0];        n = r[1];        for(j=1;j<i;j++)        {            r[j] = m + n;            m = n;            n = r[j+1];        }    }    return r;}

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[Leetcode]-Pascal's Triangle II