java - 原地旋转 NxN 矩阵 90 度时出现逻辑错误

Question

我使用下面的代码将 NxN 矩阵向左旋转 90 度。但它有一些逻辑错误。大多数元素已经旋转，但有些元素还没有静止。请帮我更正代码。

int n = 4, x = 1, i, j, temp;
int a[][] = new int[n][n];

for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++) {
        a[i][j] = x++;
    }
}

for (i = 0; i < n / 2; i++) {
    for (j = n - 1; j >= n / 2; j--) {

        temp = a[i][j];
        a[i][j] = a[n - 1 - i][j];
        a[n - 1 - i][j] = a[j][i];
        a[j][i] = a[i][n - 1 - j];
        a[i][n - 1 - j] = temp;
    }
}


for (i = 0; i < n; i++) {
    for (j = 0; j < n; j++) {
        System.out.print(a[i][j] + " ");
    }
    System.out.print("\n");
}

Answer 1

我对你的程序做了一些修改，现在它可以工作了。我提供了将矩阵左右旋转 90 度的代码。看看吧。

for (i = 0; i < n / 2; i++) {
    for (j = i; j < n - 1 - i; j++) {
        //Rotating left by 90 degrees
        temp = a[i][j];
        a[i][j] = a[j][n - 1 - i];
        a[j][n - 1 - i] = a[n - 1 - i][n - 1 - j];
        a[n - 1 - i][n - 1 - j] = a[n - 1 - j][i];
        a[n - 1 - j][i] = temp;

        /*
        //Rotating right by 90 degrees
        temp = a[i][j];
        a[i][j] = a[n - 1 - j][i];
        a[n - 1 - j][i] = a[n - 1 - i][n - 1 - j];
        a[n - 1 - i][n - 1 - j] = a[j][n - 1 - i];
        a[j][n - 1 - i] = temp;
        */
    }
}