/
product_of_array_exclude_itself.cpp
47 lines (45 loc) · 1.36 KB
/
product_of_array_exclude_itself.cpp
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class Solution {
public:
/**
* @param A: Given an integers array A
* @return: A long long array B and B[i]= A[0] * ... * A[i-1] * A[i+1] * ... * A[n-1]
*/
vector<long long> productExcludeItself(vector<int> &nums) {
// write your code here
int size = nums.size();
if (size < 2) { // why size == 1 returns [1] ?
vector<long long> ans;
if (size == 1) {
ans.push_back(1);
}
return ans;
}
vector<long long> left(size, 0);
vector<long long> right(size, 0);
for (int i = 0; i < nums.size(); i++) {
if (i == 0) {
left[i] = nums[i];
} else {
left[i] = left[i - 1] * nums[i];
}
}
for (int i = size - 1; i >= 0; i--) {
if (i == size - 1) {
right[i] = nums[i];
} else {
right[i] = right[i + 1] * nums[i];
}
}
vector<long long> ans (size, 0);
for (int i = 0; i < size; i++) {
if (i == 0) {
ans[i] = right[i + 1];
} else if (i == size - 1) {
ans[i] = left[i - 1];
} else {
ans[i] = left[i - 1] * right[i + 1];
}
}
return ans;
}
};