剑指 66. 构建乘积数组 🌶

剑指 Offer 66. 构建乘积数组

和力扣238. 除自身以外数组的乘积相同

//时间On，空间O1
func productExceptSelf(nums []int) []int {
    if len(nums) <= 1 {
        return nums
    }
    n := len(nums)
    res := make([]int, n)
    left, right := make([]int, n), make([]int, n)
    left[0], right[n - 1] = 1, 1
    for i := 1; i < n; i++ {               //左边到i的数的数组
        left[i] = left[i-1] * nums[i-1]
    }
    for i := n - 2; i >= 0; i-- {          //右边到i的数的数组
        right[i] = right[i+1] * nums[i+1]
    }
    for i := 0; i < n; i++ {                //左右相乘，即为目标数组的值
        res[i] = left[i] * right[i]
    }
    return res
}