JavaScript解决那些常见的算法题

for (var i = 0; i <= 20; i++) {
    for (var j = 0; j <= 33; j++) {
        for (var z = 0; z <= 100; z++) {
            if ((i + j + z == 100) && (5 * i + 3 * j + z / 3 == 100)) {
                 document.write('公鸡：' + i + '母鸡：' + j + '小鸡：' + z + '<hr/>');
            }
        }
    }
}

for (var i = 0; i <= 20; i++) {
    for (var j = 0; j <= 33; j++) {
        z = 100 - i - j;
        if ((z % 3 == 0) && (5 * i + 3 * j + z / 3 == 100)) {
            document.write('公鸡：' + i + '母鸡：' + j + '小鸡：' + z + '<hr/>');
        }
    }
}

var count = 0;                    
for (var i = 1; i <= 4; i++) {          
    for (var j = 1; j <= 4; j++) {         
        if (i != j) {            
            for (var k = 1; k <= 4; k++) {
                if (j != k && k != i) {
                    console.log("" + i + j + k);
                    count++;
                }
            }
        }
    }
};
console.log("共" + count + "次循环");

for (var r = 0, str = ""; r < 8; r++) {
    for (var c = 0; c < 8; c++) {
        str += (r + c) % 2 == 0 ? "□" : "■";
    }
    str += "\n";
}
console.log(str);

function start(a,b){
    var x=0;
    var y=0;
    for(var x=0;x<a; x++){
        y=48-x;
        if (2*x+4*y==b){
            console.log("鸡有"+x+"只,兔有"+y+"只");
        }
    }
}

function decompose(n){
    var arr=[];                   
    for(var i=2;i<=n;i++){        
        while(n%i==0){           
            arr.push(i);          
            n/=i;                 
        }
    }
    return arr.join("*");          
}
console.log(decompose(90));

function doubleBall() {
    var reds = [];
    while (reds.length < 6) {
        var r = parseInt(Math.random() * 33 + 1);
        for (var i = 0; i < reds.length; i++) {
            if (r == reds[i]) {
                break;
            };
            if (i == reds.length) {
                reds.push(r);
            };
        }
    }
    function cmp(a, b) { 
        return a - b; 
    }
    reds.sort(cmp);
    var blue = parseInt(Math.random() * 16 + 1);
    return String(reds) + "|" + blue;
}
document.write(doubleBall());

function fib(n){
    if(n<3){
         return 1;
    }else{
        return fib(n-1)+fib(n-2);
    }
}
console.log(fib(10));

function fib(n){
    if(n<3){
        return 1;
    }else{
        var a=1,b= 1,c;
        for(var i=3;i<=n;i++){
            c=a+b;
            a=b;
            b=c;
        }
        return c;
    }
}
console.log(fib(10));

for(var i=10,sum=1;i>1;i--){
    sum+=1;
    sum*=2;
}
console.log(sum);

var sum=0;
for(var i=1;i<=100;i++){
    if(i%2==1){
        sum+=i;
    }
}
document.write('1~100之间奇数的和为：'+sum+'<hr/>');

var sum=0;
for(var i=1;i<=100;i++){
    if(i%2==0){
        sum+=i;
    }
}
document.write('1~100之间偶数的和为：'+sum+'<hr/>');

function isPrime(n){
    if(n<=3){
        return true;
    }else{
        for(var i=2;i<=Math.sqrt(n);i++){ 
            if(n%i==0){
                return false; 
            } 
        }                      
    }                       
}
console.log(isPrime(17));

document.write('<table border="1" cellpadding="0" cellspacing="0" bgcolor="#ABCDEF" width="80%">');
    for(var i=1;i<=9;++i){
        document.write('<tr>');
            for(var j=1;j<=i;j++){
                document.write('<td>'+i+'x'+j+'='+(i*j)+'</td>');
            }
        document.write('</tr>');
    }
document.write('</table>');

document.write("<table border='1' cellpadding='0' cellspacing='0' bgcolor='aqua' width='80%'>");
    for(var i=9;i>=1;i--){
        document.write('<tr>');
            for(var j=1;j<=i;j++){
                document.write('<td>'+i+'x'+j+'='+(i*j)+'</td>');
            }
        document.write('</tr>');
    }
document.write('</table>');

function triangle(ln){
    for(var r=1;r<=ln;r++){                  
        for(var i= 1,str="";i<=ln+r-1;i++){  
            str+=i<=ln-r?" ":"*";            
        }
        console.log(str);
    }
}
triangle(5)