我似乎在代码中找不到任何逻辑错误，但仍无法按预期工作

Question

Given an array of ints, return true if the value 3 appears in the array exactly 3 times, and no 3's are next to each other.

I'm just a beginner programmer having some trouble at a codingbat lesson. The logic seems fine. I've explained to the "rubber duck" a thousand times and I found no problem with it. All codingbat tests run as expected, except for the "other tests" tabs, which I cannot see the specific numbers in the array and cannot compare with the code. I'm really puzzled by this one, hope you can help me!

public boolean haveThree(int[] a) {

    int count = 0;           //to count the appearences of 3
    boolean doLado = false;   //to check if a 3 is next to another 3

    if(a[0] == 3)    // check if first index is 3
        count++;      // add one if it is

    for(int i=1; i<a.length ; i++) { //loop starting at 1 to check rest of array

        if(a[i] == 3) {     // check if i is 3
            if(a[i-1] == a[i]) // if i its 3, check if the previous index was also 3
                return false;   // if it was indeed {..,3,3,..} return false
            else
                count++;        // else add 1 to the counter
        }
    }

    if(count == 3) //if counter of 3s equals 3 return true
        return true;

    return false; //else return false
}


tests                                  Expected  Run        
haveThree([3, 1, 3, 1, 3])----------- → true    true    OK  
haveThree([3, 1, 3, 3])---------------→ false   false   OK  
haveThree([3, 4, 3, 3, 4])------------→ false   false   OK  
haveThree([1, 3, 1, 3, 1, 2])---------→ false   false   OK  
haveThree([1, 3, 1, 3, 1, 3])---------→ true    true    OK  
haveThree([1, 3, 3, 1, 3])------------→ false   false   OK  
haveThree([1, 3, 1, 3, 1, 3, 4, 3])---→ false   false   OK  
haveThree([3, 4, 3, 4, 3, 4, 4])----- → true    true    OK  
haveThree([3, 3, 3])------------------→ false   false   OK  
haveThree([1, 3])---------------------→ false   false   OK  
haveThree([3])------------------------→ false   false   OK  
haveThree([1])------------------------→ false   false   OK  

other tests-----------------------------X

Answer 1

You don't handle null and you don't use doLado ; also you don't need an if at the end to test for count == 3 . I would simplify it to something like

public boolean haveThree(int[] a) {
    if (a == null || a.length < 3) {
        return false;
    }
    int count = 0;
    for (int i = 0; i < a.length; i++) {
        if (a[i] == 3) {
            if (i > 0 && a[i - 1] == 3) {
                return false;
            }
            count++;
        }
    }
    return count == 3;
}

Answer 2

null check is missing in your code to check if array a is null.

You code will work fine if you add null check alone.