LeetCode 238. Product of Array Except Self

解题思路:l两个循环,第一个从0到i-1,累乘,第二个从n到i+1,累乘.

class Solution {public:   vector<int> productExceptSelf(vector<int>& nums) {    int N = nums.size();    vector<int> res(N,1);        for(int i=0; i<N; i++){        if (i==0)   res[i] = 1;        else res[i] = res[i-1]*nums[i-1];    }        int tmp = 1;    for(int i=N-1; i>=0; i--){        res[i] *= tmp;        tmp *= nums[i];    }        return res;}};