Google Chrome开发者工具在嵌套for循环中不一致

Question

While trying to solve this project euler problem (using Google chrome - snippets feature in developer tools to code and execute) , I encountered a strange behavior.

var palFound = false;
isPal = function (word) {
    var wordCount = word.length;
    for (i = 0; i < wordCount; i++) {
        if (word[i] != word[wordCount - i - 1]) {
            return false;
        }
    }
    return true;
}

for (var k = 999; k >= 100; k--) {
    for (var j = 999; j >= 100; j--) {
        var prod = k * j,
            prodString = prod + '';
        if (isPal(prodString)) {
            console.log(prod, k, j);
            palFound = true;
            break;
        }

    }
    if (palFound) {
        break;
    }
}

Above code should ideally display the first encountered palindrome product and should break.But when executed the above code displays a wrong answer 580085 which is a product of 995 and 583.

But when the for loops limit are changed to 999 to 900 (as shown below), correct answer is displayed - 906609 which is a product of 993 and 913.

for(var k=999;k >=900;k--){
for(var j=999;j>=900;j--)

ideally, 993 and 913 should be encountered first, instead of 995 and 583. I am curious to know why is this happening?.

Answer 1

For each k value in your outer loop your inner loop counts down from 999 to 100, so when k is 995 then j counts down to 583 finds a palindrome and the code breaks out of your loop.

When you amend j to only count down to 900 it does not reach 583 and so the first palidrome you now reach is 993 * 913.