英文:
why wont this return false with the given array
问题
int[] array2 = new int[]{1, 2, 6, 6, 3, 1};
// 该方法检查给定的数组内容在数组反转时是否保持不变
public static boolean verify(int[] array, int index) { // 方法接受数组和索引号
if ((array[index] == array[array.length - index - 1]) && (index < array.length / 2)) {
System.out.print("true/");
verify(array, ++index); // 增加索引号以检查数组中的下一个值
return true;
} else
System.out.println("..false..");
return false;
}
英文:
int[] array2 = new int[]{1,2,6,6,3,1,};
//method checks if the given array contents remain the same when array is reversed
public static boolean verify(int[] array, int index) {//method takes array and an index number
if ((array[index] == array[array.length - index-1]) && (index < array.length/2)) {
System.out.print("true/");
verify(array, ++index);// increase index number to check the next values in the th array
return true;
} else
System.out.println("..false..");
return false;
}
答案1
得分: 0
你可能想要像这样做：
public static boolean verify(int[] array, int index) {
if (array[index] == array[array.length - index - 1]) {
if (index < array.length / 2)
return verify(array, ++index);
return true;
} else {...}
return false;
}
你需要确保子值传播到父值，还需要以不同的方式检查索引：如果索引超过数组长度的一半，也不算错误，你只是不想检查这种索引的值。
英文:
You probably want to do something like this:
public static boolean verify(int[] array, int index) {
if (array[index] == array[array.length - index-1]) {
if(index < array.length/2)
return verify(array, ++index);
return true;
} else {...}
return false;
}
You need to make sure the child value gets propagated to parent, and also check the index differently: It's not wrong, if the index is over a half of the array's length, you just don't want to check the values for such index.
答案2
得分: 0
最好的做法是在方法中不要打印结果，而只打印返回值。
public static boolean verify(int[] array, int index) {
// 不要超过中间位置
if (index >= array.length/2) {
return true;
}
// 一旦发现比较不相等的情况就立即返回 false
if(array[index] != array[array.length-index-1]) {
return false;
}
// 尝试下一个值
return verify(array, index + 1);
}
System.out.println(verify(new int[] {1,2,3,3,3,2,1}, 0));
System.out.println(verify(new int[] {1,2,3,3,2,1}, 0));
System.out.println(verify(new int[] {1,2,4,3,3,2,1}, 0));
System.out.println(verify(new int[] {1,2,4,3,3,4,2,1}, 0));
System.out.println(verify(new int[] {1}, 0));
System.out.println(verify(new int[] {1,2}, 0));
输出结果：
true
true
false
true
true
false
英文:
It's best to not print the result in the method but to just print the return value.
public static boolean verify(int[] array, int index) {
// don't go passed the middle
if (index >= array.length/2) {
return true;
}
// return as soon as a false comparison is found
if(array[index] != array[array.length-index-1]) {
return false;
}
// Try the next value
return verify(array, index + 1);
}
System.out.println(verify(new int[] {1,2,3,3,3,2,1}, 0));
System.out.println(verify(new int[] {1,2,3,3,2,1}, 0));
System.out.println(verify(new int[] {1,2,4,3,3,2,1}, 0));
System.out.println(verify(new int[] {1,2,4,3,3,4,2,1}, 0));
System.out.println(verify(new int[] {1}, 0));
System.out.println(verify(new int[] {1,2}, 0));
Prints
true
true
false
true
true
false
</details>
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