Problem – Product of Array Except Self
https://leetcode.com/problems/
Given an array nums
of n integers where n > 1, return an array output
such that output[i]
is equal to the product of all the elements of nums
except nums[i]
.
Example:
**Input:** [1,2,3,4] **Output:** [24,12,8,6]
Constraint: It’s guaranteed that the product of the elements of any prefix or suffix of the array (including the whole array) fits in a 32 bit integer.
Note: ** Please solve it **without division and in O(n).
Follow up:
Could you solve it with constant space complexity? (The output array does not count as extra space for the purpose of space complexity analysis.)
Group Anagrams ES6 solution
#1 O(n^2) time complexity solution
/\*\*@param {number[]}
nums@return {number[]}\*/
var productExceptSelf = function(nums) {
let result = [];
result[nums.length - 1] = 1;
for(let i = nums.length - 2; i >= 0; i--){
result[i] = result[i + 1] * nums[i + 1];
}
let left = 1;
for(let i = 0; i < nums.length; i++){
result[i] = result[i] * left;
left = left * nums[i];
}
return result;
};
runtime 140ms
#2 O(n) time complexity solution
/\*\*@param {number[]}
nums@return {number[]}\*/
var productExceptSelf = function(nums) {
let result = [];
result[nums.length - 1] = 1;
for(let i = nums.length - 2; i >= 0; i--){
result[i] = result[i + 1] * nums[i + 1];
}
let left = 1;
for(let i = 0; i < nums.length; i++){
result[i] = result[i] * left;
left = left * nums[i];
}
return result;
};
runtime 84ms
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