Algorithm exercise four: print Yang Hui triangle

Rule: 1. The sum of the nth layer equals the n power of 2; 2. Starting from the third level the number equals the sum of the two numbers above it; 3. The length of each line equals n, and the loop n times;

         　　 functiontext (n) {vararr = [];//Results                varARR1 = [];//Relay                //generate Yang Hui triangle data                 for(vari = 1; I <= N; i++) {arr1= [1];//The first value is "1"                     for(varj = 1; J < I; J + +){                        if(j = = I-1) {Arr1[j]= 1;//the last value is "1"}Else{Arr1[j]= Arr[i-2][j] + arr[i-2][j-1];//The median value is the number of two values above it and}} arr.push (ARR1); }                   //iterate through arrays, print data                 for(varK = 0;k < arr.length; k++){                    vari = "; varARR2 = [];  for(varL = 0; L < arr.length-k;l++) {Arr2.push (i); } console.log (Arr2.join (") + arr[k].join (' ') }}} text (10);

Algorithm exercise four: print Yang Hui triangle