LEETCODEMedium
Product of Array Except Self
Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i].
The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer.
You must write an algorithm that runs in O(n) time and without using the division operation.
Example 1:
Input: nums = [1,2,3,4] Output: [24,12,8,6]
Example 2:
Input: nums = [-1,1,0,-3,3] Output: [0,0,9,0,0]
Constraints:
2 <= nums.length <= 105-30 <= nums[i] <= 30- The input is generated such that
answer[i]is guaranteed to fit in a 32-bit integer.
Follow up: Can you solve the problem in O(1) extra space complexity? (The output array does not count as extra space for space complexity analysis.)
풀이 TypeScript
function productExceptSelf(nums: number[]): number[] {
const n = nums.length;
const answer: number[] = new Array(n);
answer[0] = 1;
for (let i = 1; i < n; i++) {
answer[i] = answer[i - 1] * nums[i - 1];
}
let suffix = 1;
for (let i = n - 1; i >= 0; i--) {
answer[i] = answer[i] * suffix;
suffix *= nums[i];
}
return answer;
};
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