Given a non-negative integer *numRows*, generate the first*numRows*of Pascal's triangle.  In Pascal's triangle, each number is the sum of the two numbers directly above it. **Example:** ~~~ Input: 5 Output: [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ] ~~~ ``` var generate = function(numRows) { var ans = []; for(var i=0;i<numRows;i++){ if(i===0){ ans[i]=[1]; continue; } ans[i] = []; for(var j=0;j<=i;j++){ if(j===0){ ans[i][j] = ans[i-1][j]; }else if(j===i){ ans[i][j] = ans[i-1][j-1]; }else{ ans[i][j] = ans[i-1][j-1] + ans[i-1][j] } } } return ans; }; ``` ``` var generate = function (numRows) { let arr = []; for (let i = 0; i < numRows; i++) { let one = []; for (let j = 0, length = i + 1; j < length; j++) { if (j == 0 || j == i) one.push(1); else { one.push(arr[i - 1][j - 1] + arr[i - 1][j]); } } arr.push(one); } return arr; }; ```