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Given a non-empty array, return true if there is a place to split the array so that the sum of the numbers on one side is equal to the sum of the numbers on the other side.
canBalance([1, 1, 1, 2, 1]) → true//i thought since 1+1 is not equal to 2+1 it should be false?
canBalance([2, 1, 1, 2, 1]) → false//i thought since 2+1 is equal to 2+1 it should be true??
canBalance([10, 10]) → true
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But, they want us to split the array into two pieces
front and back
break at what index or point? just randomly we can break?
public boolean canBalance(int[] nums) {
for (int i = 0; i < nums.length; i++) {
int leftTotal=0;
leftTotal=leftTotal+nums[i];
for (int j = nums.length-1; j >i; j--) {
int rightTotal=0;
rightTotal=rightTotal+nums[i];
if(rightTotal==leftTotal){
return true;
}
}
}
return false;
}
Expected Run
canBalance([1, 1, 1, 2, 1]) → true true OK
canBalance([2, 1, 1, 2, 1]) → false true X
canBalance([10, 10]) → true true OK
canBalance([10, 0, 1, -1, 10]) → true true OK
canBalance([1, 1, 1, 1, 4]) → true true OK
canBalance([2, 1, 1, 1, 4]) → false true X
canBalance([2, 3, 4, 1, 2]) → false true X
canBalance([1, 2, 3, 1, 0, 2, 3]) → true true OK
canBalance([1, 2, 3, 1, 0, 1, 3]) → false true X
canBalance([1]) → false false OK
canBalance([1, 1, 1, 2, 1]) → true true OK
other tests
X
public class CanBalance {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] ar={1,1,1,2,1};
System.out.println("canBalance value is--->"+canBalance(ar));
}
public static boolean canBalance(int[] nums) {
for (int i = 0; i < nums.length; i++) {
int leftTotal=0;
leftTotal=leftTotal+nums[i];
for (int j = nums.length-1; j >i; j--) {
int rightTotal=0;
rightTotal=rightTotal+nums[i];
if(leftTotal==rightTotal){
return true;
}
}
}
return false;
}
}
public class CanBalance {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[] ar={1,1,1,2,1};
System.out.println("canBalance value is--->"+canBalance(ar));
}
public static boolean canBalance(int[] nums) {
for (int i = 0; i < nums.length; i++) {
int leftTotal=0;
leftTotal=leftTotal+nums[i];
System.out.println("i is " + i + " leftTotal is " + leftTotal);
for (int j = nums.length-1; j >i; j--) {
int rightTotal=0;
rightTotal=rightTotal+nums[i];
System.out.println("j is " + j + " rightTotal is " + leftTotal);
if(leftTotal==rightTotal){
return true;
}
}
}
return false;
}
}
The output isrightTotal=rightTotal+nums[i];
is wrong. rightTotal should have equal to 3(at that point). You have i where you should have j.
public boolean canBalance(int[] nums) {
int leftTotal=0;
int rightTotal=0;
for (int i = 0; i < nums.length; i++) {
leftTotal=leftTotal+nums[i];
// System.out.println("i is " + i + " leftTotal is " + leftTotal);
for (int j = nums.length-1; j >i; j--) {
rightTotal=rightTotal+nums[j];
// System.out.println("j is " + j + " rightTotal is " + rightTotal);
if(leftTotal==rightTotal){
return true;
}
}
}
return false;
}
Expected Run
canBalance([1, 1, 1, 2, 1]) → true true OK
canBalance([2, 1, 1, 2, 1]) → false false OK
canBalance([10, 10]) → true true OK
canBalance([10, 0, 1, -1, 10]) → true true OK
canBalance([1, 1, 1, 1, 4]) → true false X
canBalance([2, 1, 1, 1, 4]) → false false OK
canBalance([2, 3, 4, 1, 2]) → false true X
canBalance([1, 2, 3, 1, 0, 2, 3]) → true false X
canBalance([1, 2, 3, 1, 0, 1, 3]) → false false OK
canBalance([1]) → false false OK
canBalance([1, 1, 1, 2, 1]) → true true OK
other tests
OK
public class CanBalance {
public static void main(String[] args) {
// TODO Auto-generated method stub
//int[] ar={1,1,1,2,1};
//System.out.println("canBalance value is--->"+canBalance(ar));
//2, 1, 1, 2, 1
int[] ar1={1, 2, 3, 1, 0, 1, 3};
System.out.println("canBalance value is--->"+canBalance(ar1));
}
public static boolean canBalance(int[] nums) {
int leftTotal=0;
int rightTotal=0;
for (int i = 0; i < nums.length; i++) {
leftTotal=leftTotal+nums[i];
System.out.println("i is " + i + " leftTotal is " + leftTotal);
for (int j = nums.length-1; j >i; j--) {
rightTotal=rightTotal+nums[j];
System.out.println("j is " + j + " rightTotal is " + rightTotal);
if(leftTotal==rightTotal){
return true;
}
}
}
return false;
}
}
My solution has nested for loops . Something like
for( whole array){
for( front){ add them}
for( back){add them}
if front equals back return true
}
int leftTotal=0;
int rightTotal=0;
public boolean canBalance(int[] nums) {
int leftTotal=0;
for (int i = 0; i < nums.length; i++) {
leftTotal=leftTotal+nums[i];
// System.out.println("i is " + i + " leftTotal is " + leftTotal);
int rightTotal=0;
for (int j = nums.length-1; j >i; j--) {
rightTotal=rightTotal+nums[j];
//System.out.println("j is " + j + " rightTotal is " + rightTotal);
}
if(leftTotal==rightTotal){
return true;
}
}
return false;
}
int rightTotal=0;
for (int j = nums.length-1; j >i; j--) {
do i need to define ....I don't know. I can't really understand your code(thinking). My thoughts :
public class CanBalance {
public static void main(String[] args) {
int[] ar1={2, 1, 1, 2, 1};
System.out.println("canBalance value is--->"+canBalance(ar1));
}
public static boolean canBalance(int[] nums) {
int leftTotal=0;
for (int i = 0; i < nums.length; i++) {
leftTotal=leftTotal+nums[i];
System.out.println("i is " + i + " leftTotal is " + leftTotal);
int rightTotal=0;
for (int j = nums.length-1; j >i; j--) {
rightTotal=rightTotal+nums[j];
System.out.println("j is " + j + " rightTotal is " + rightTotal);
}
if(leftTotal==rightTotal){
return true;
}
}
return false;
}
}
i is 0 leftTotal is 2any improvements, modifications, refinement to above code? how does your code looks like?
j is 4 rightTotal is 1
j is 3 rightTotal is 3
j is 2 rightTotal is 4
j is 1 rightTotal is 5
i is 1 leftTotal is 3
j is 4 rightTotal is 1
j is 3 rightTotal is 3
j is 2 rightTotal is 4
i is 2 leftTotal is 4
j is 4 rightTotal is 1
j is 3 rightTotal is 3
i is 3 leftTotal is 6
j is 4 rightTotal is 1
i is 4 leftTotal is 7
canBalance value is--->false
YOu need to test for equality after each time you add the right value.
public class CanBalance {
public static void main(String[] args) {
int[] ar={4, 2, 3, 3};
System.out.println("canBalance value is--->"+canBalance(ar));
}
public static boolean canBalance(int[] nums) {
boolean result = false;
int front = 0;
int back = 0;
for(int i = 0; i < nums.length; i++){
for(int f = 0; f < i + 1 ; f++){
front += nums[f];
System.out.println("f is " + f + " front is " + front);
}
for(int b = i + 1; b < nums.length ; b++){
back += nums[b];
System.out.println("b is " + b + " back is " + back);
}
if(front == back){
result = true;
break;
}
else{
front = 0;
back = 0;
}
}
return result;
}
}
Output was Only difference with your code is where you test for equality
public boolean canBalance(int[] nums) {
int leftTotal=0;
int rightTotal=0;
for (int i = 0; i < nums.length; i++) {
leftTotal=leftTotal+nums[i];
// System.out.println("i is " + i + " leftTotal is " + leftTotal);
// int rightTotal=0;
for (int j = nums.length-1; j >i; j--) {
rightTotal=rightTotal+nums[j];
//System.out.println("j is " + j + " rightTotal is " + rightTotal);
}
if(leftTotal==rightTotal){
return true;
}
}
return false;
}
Expected Run
canBalance([1, 1, 1, 2, 1]) → true false X
canBalance([2, 1, 1, 2, 1]) → false false OK
canBalance([10, 10]) → true true OK
canBalance([10, 0, 1, -1, 10]) → true true OK
canBalance([1, 1, 1, 1, 4]) → true false X
canBalance([2, 1, 1, 1, 4]) → false false OK
canBalance([2, 3, 4, 1, 2]) → false false OK
canBalance([1, 2, 3, 1, 0, 2, 3]) → true false X
canBalance([1, 2, 3, 1, 0, 1, 3]) → false false OK
canBalance([1]) → false false OK
canBalance([1, 1, 1, 2, 1]) → true false X
other tests
OK
int rightTotal=0;
for (int i = 0; i < nums.length; i++) {
why above code fails some tests if i move rightSum initialization line to the top of outer for loop rather than inner for loop??because you are not resetting the total value.
i is 0 leftTotal is 2
j is 4 rightTotal is 1
j is 3 rightTotal is 3
j is 2 rightTotal is 4
j is 1 rightTotal is 5
i is 1 leftTotal is 3
j is 4 rightTotal is 1
j is 3 rightTotal is 3
j is 2 rightTotal is 4
i is 2 leftTotal is 4
j is 4 rightTotal is 1
j is 3 rightTotal is 3
i is 3 leftTotal is 6
j is 4 rightTotal is 1
i is 4 leftTotal is 7
canBalance value is--->false
why above code fails some tests if i move rightSum initialization line to the top of outer for loop rather than inner for loop??
because you are not resetting the total value.
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