leetcode/algorithms/ProductofArrayExceptSelf/solve.cpp at master · int32bit/leetcode · GitHub

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#include <vector>
#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
static inline void print(const vector<int> &a) {
	for_each(begin(a), end(a), [](int i){cout << i << ' ';});
	cout << endl;
}
class Solution {
public:
    /*
    vector<int> productExceptSelf(vector<int>& nums) {
	    if (nums.empty()) // 空
		    return vector<int>();
	    if (nums.size() == 1) { //只有一个元素，返回{0}
		    return vector<int>({0});
	    }
	    auto n = nums.size();
	    vector<int> a(n, 1), b(n, 1);
	    for (auto i = 1; i < n; ++i) {
		    a[i] = a[i - 1] * nums[i - 1];
		    b[i] = b[i - 1] * nums[n - i];
	    }
	    for (auto i = 0; i < n; ++i) {
		    a[i] *= b[n - i - 1];
	    }
	    return a;
    }
    */
    vector<int> productExceptSelf(vector<int> &nums) {
	    if (nums.empty()) // 空
		    return vector<int>();
	    if (nums.size() == 1) { //只有一个元素，返回{0}
		    return vector<int>({0});
	    }
	    int n = nums.size();
	    vector<int> result(n, 1);
	    for (int i = 1; i < n; ++i)
		    result[i] = result[i - 1] * nums[i - 1];
	    int product = 1;
	    for (int i = n - 2; i >= 0; --i) {
		    product *= nums[i + 1];
		    result[i] *= product;
	    }
	    return result;

    }
};
int main(int argc, char **argv)
{
	Solution solution;
	vector<int> v = {1,2,3,4};
	auto result = solution.productExceptSelf(v);
	print(result);
	return 0;
}