下面是用JS写的一个简单的二分查找代码。这段代码返回 -1 而它应该返回 20。我环顾四周后所做的事情:
将“while(min < max)”替换为“while(min <= max)”会在 KhanAcademy 上弹出错误。
我使用了 Math.floor 函数,由于某种原因它弹出错误“env.Math.floor 不是一个函数”,所以我改用了“Math.round”。
var doSearch = function(array, targetValue) {
var min = 0;
var max = array.length - 1;
var guess;
while (min < max) {
guess = Math.round((max + min) / 2);
if (array[guess] === targetValue) {
return guess;
} else if (array[guess] < targetValue) {
min = guess + 1;
} else {
max = guess - 1;
}
}
return -1;
};
var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97];
var result = doSearch(primes, 73);
console.log("Found prime at index " + result);
//print (primes[]);
//Program.assertEqual(doSearch(primes, 73), 20);
最佳答案
我建议在分配新值时将 min
rps max
值更改为 guess
。
此外,我建议将 Math.round
更改为 Math.floor
。
(小提示:返回后,if
子句结束,所以不需要else if
。)
var doSearch = function (array, targetValue) {
var min = 0;
var max = array.length - 1;
var guess;
while (min < max) {
guess = Math.floor((max + min) / 2);
if (array[guess] === targetValue) {
return guess;
}
if (array[guess] < targetValue) {
min = guess;
} else {
max = guess;
}
}
return -1;
};
var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97],
result = doSearch(primes, 73);
console.log("Found prime at index " + result);
关于javascript - 可汗学院算法挑战 : Binary Search,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/40007427/