3-编程练习

杨辉三角

function yanghui(num){ let ret=[]; for(let i=0;i<num;i++){ let temp=new Array(i+1).fill(1); for(let j=1;j<i;j++){ temp[j]=ret[i-1][j-1]+ret[i-1][j]; } ret.push(temp); } return ret; } console.log(yanghui(5))

结果： [ [ 1 ], [ 1, 1 ], [ 1, 2, 1 ], [ 1, 3, 3, 1 ], [ 1, 4, 6, 4, 1 ] ]

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编写函数输出1~1000的所有对称数

function duichengshu(num){ var arr=[]; while(--num>10){ var reverseNum=num.toString().split('').reverse().join(''); //依次把每个值分开为多个数字组成的数组，然后颠倒顺序 //再重新连接为一个数字字符串 (reverseNum==num)&&(arr.push(num)); } return arr; } var ret=duichengshu(1000); console.log(ret);

结果： [ 999, 989, 979, 969, 959, 949, 939, 929, 919, 909, 898, 888, 878, 868, 858, 848, 838, 828, 818, 808, 797, 787, 777, 767, 757, 747, 737, 727, 717, 707, 696, 686, 676, 666, 656, 646, 636, 626, 616, 606, 595, 585, 575, 565, 555, 545, 535, 525, 515, 505, 494, 484, 474, 464, 454, 444, 434, 424, 414, 404, 393, 383, 373, 363, 353, 343, 333, 323, 313, 303, 292, 282, 272, 262, 252, 242, 232, 222, 212, 202, 191, 181, 171, 161, 151, 141, 131, 121, 111, 101, 99, 88, 77, 66, 55, 44, 33, 22, 11 ]

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