118. Pascal's Triangle.c

/*
118. Pascal's Triangle

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]
]
*/

/**
 * 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(intnumRows, int**columnSizes) {
    inti, j;
    int*buff, **p;
    p=malloc(numRows*sizeof(int*));
    *columnSizes=malloc(numRows*sizeof(int));
    //assert(p && *columnSizes);
    for (i=1; i <= numRows; i++) {
        buff=malloc(i*sizeof(int));
        //assert(buff);
        p[i-1] =buff;
       (*columnSizes)[i-1] =i;
        buff[0] =1;
        for (j=1; j<i-1; j++) {
            buff[j] =p[i-2][j-1] +p[i-2][j];
       }
        buff[i-1] =1;
   }
    returnp;
}


/*
Difficulty:Easy
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*/