public class Solution {
public int[] productExceptSelf(int[] nums) {
int len = nums.length;
int[] ans = new int[len];
for (int i = 0, temp = 1; i < len; i++) {
ans[i] = temp;
temp *= nums[i];
}
for (int i = len - 1, temp = 1; i >= 0; i--) {
ans[i] *= temp;
temp *= nums[i];
}
return ans;
}
}
After the first for loop, nums[i]
is equal to the product of the numbers from 0
to i - 1
. At each iteration of the second for loop, nums[i]
is multiplied by the product of the numbers from i + 1
to len - 1
. Therefore, after the two for loops, nums[i] = nums[0] * nums[1] * ... * nums[i-1] * ... * nums[i+1] * ... * nums[len-1]
.
Time Complexity: O(n)
Extra Space: O(1)
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