我有一个代码，在按键时不会接受空格，但它不起作用。

Question

这是我的代码：

void remove_bottom_up(int[] arr1, int[] arr2) {
    boolean[][] memoized = calculate_memoization_table(arr1, arr2);
    backtrack(arr1, arr2, 0, 0, memoized, new Stack<>());
}

/**
 * Has a polynomial runtime complexity: O(length(arr1) * length(arr2))
 */
boolean[][] calculate_memoization_table(int[] arr1, int[] arr2) {

    boolean[][] memoized = new boolean[arr1.length + 1][arr2.length + 1];
    memoized[arr1.length][arr2.length] = true;

    for (int i1 = arr1.length - 1; i1 >= 0; i1--) {
        for (int i2 = arr2.length; i2 >= 0; i2--) {

            if ((i2 < arr2.length) && (arr1[i1] == arr2[i2])) {
                memoized[i1][i2] = memoized[i1 + 1][i2 + 1];
            }
            memoized[i1][i2] |= memoized[i1 + 1][i2];
        }
    }
    return memoized;
}

/**
 * Might have exponential runtime complexity.
 *
 * E.g. consider the instance of the problem, when it is needed to remove
 * arr2 = [1,1,1] from arr1 = [1,1,1,1,1,1,1].
 *
 * There are 7!/(3! * 4!) = 35 ways to do it.
 */
void backtrack(int[] arr1, int[] arr2, int i1, int i2, boolean[][] memoized, Stack<Integer> stack) {

    if (!memoized[i1][i2]) {
        // arr2 can't be removed from arr1
        return;
    }

    if (i1 == arr1.length) {
        // at this point, instead of printing the variant of arr1 after removing of arr2
        // we can just collect this variant into some other container
        // e.g. allVariants.add(stack.clone())
        System.out.println(stack);
        return;
    }

    if ((i2 < arr2.length) && (arr1[i1] == arr2[i2])) {
        backtrack(arr1, arr2, i1 + 1, i2 + 1, memoized, stack);
    }

    stack.push(arr1[i1]);
    backtrack(arr1, arr2, i1 + 1, i2, memoized, stack);
    stack.pop();
}

#distype，＃val是文本输入的id。

Answer 1

您正在将onKeyDown侦听器附加到body。不应该输入本身？此外，它应该是e.which || e.keyCode。

像这样：

$("#distype").on("keydown", function (e){
    console.log(this.value);
      if (e.which && e.target.selectionStart === 0 || e.keyCode === 32 &&  e.target.selectionStart === 0) {
        return false;
      }  
}