Practice 2015 FRQ Question 1 • 6 min read

public static int arraySum(int[] arr) {
    int total = 0;  // initialize total to 0

    for(int num : arr) // loop through each number in the array
        total += num; // add the number to the total
    return total; // return the total
}

// Proof it works

int[] arr = {1, 2, 3, 4, 5};
System.out.println(arraySum(arr));

public static int[] rowSums(int[][] arr2D) {
    int[] sums = new int[arr2D.length]; // create an array to store row sums
    
    for (int i = 0; i < arr2D.length; i++) { // iterate through each row
        int rowSum = 0; 
        
        for (int j = 0; j < arr2D[i].length; j++) { // iterate through each element in the row
            rowSum += arr2D[i][j]; // add the element to the row sum
        }
        
        sums[i] = rowSum; // store the sum of the current row in the sums array
    }
    
    return sums; // return the array of row sums
}

// Proof it works

int[][] arr2D = {
    {1, 2, 3}, 
    {4, 5, 6}, 
    {7, 8, 9}
};
int[] sums = rowSums(arr2D);
System.out.println(Arrays.toString(sums)); 

public static boolean isDiverse(int [ ] [ ] arr2D) {
    int[] sums = rowSums(arr2D); // get the row sums
    
    for (int i = 0; i < sums.length; i++) { // iterate through each row sum
        for (int j = i + 1; j < sums.length; j++) { // iterate through each subsequent row sum
            if (sums[i] == sums[j]) { // if any two row sums are equal
                return false; // the array is not diverse
            }
        }
    }
    
    return true; // if no two row sums are equal, the array is diverse
}

// Proof it works

int[][] arr2D = {
    {1, 2, 3}, 
    {4, 5, 6}, 
    {7, 8, 9}
};
System.out.println(isDiverse(arr2D)); 

int[][] arr2D2 = {
    {1, 2, 3}, 
    {3, 2, 1}, 
    {7, 8, 9}
};
System.out.println(isDiverse(arr2D2));