0238-product-of-array-except-self.java

//Just store the left and right product (Try doing this with extra space first)
//This one is constant space because we are returning the array we created
//In first pass calculate the left product except self and in second calculate the right

classSolution {

publicint[] productExceptSelf(int[] nums) {
int[] arr = newint[nums.length];
intright = 1, left = 1;
for (inti = 0; i < nums.length; i++) {
arr[i] = left;
left *= nums[i];
 }
for (inti = nums.length - 1; i >= 0; i--) {
arr[i] *= right;
right *= nums[i];
 }
returnarr;
 }

publicint[] productExceptSelfNumsAsPrefix(int[] nums) {
int[] output = newint[nums.length];
output[0] = 1;

for (inti = 0; i < nums.length - 1; i++) output[i + 1] =
output[i] * nums[i];

for (inti = nums.length - 2; i >= 0; i--) {
output[i] = nums[i + 1] * output[i];
nums[i] = nums[i] * nums[i + 1];
 }
returnoutput;
 }
}