1.描述
Given numRows, generate the first numRows of Pascal's triangle.
For example, given numRows = 5,
Return
[
[1],
[1,1],
[1,2,1],
[1,3,3,1],
[1,4,6,4,1]
]
2.分析
3.代码
/**
* Return an array of arrays.
* The sizes of the arrays are returned as *columnSizes array.
* Note: Both returned array and *columnSizes array must be malloced, assume caller calls free().
*/
int** generate(int numRows, int** columnSizes) {
if (numRows <= 0) return NULL;
*columnSizes = (int*)malloc(sizeof(int) * numRows);
int** array = (int**)malloc(sizeof(int*) * numRows);
for (unsigned int i = 0; i < numRows; ++i) {
(*columnSizes)[i] = i + 1;
int* row = (int*)malloc(sizeof(int) * (i+1));
row[0] = 1;
for (unsigned int j = 1; j< i + 1; ++j) {
row[j] = array[i-1][j-1] + array[i-1][j];
}
row[i] = 1;
array[i] = row;
}
return array;
}
