已知数组a，给数组b赋值，b[i]=a[0]*a[1]*...a[N]/a[i]，要求时间复杂度为O(n)，除了迭代下标，不能另外声明变量，同时不能用除法。

tece.cpp

#include <iostream>
using namespace std;

void foo(int *p_a_, int *p_b_, int n_);

int main()
{
	int a[] = {1, 2, 3, 4, 5};
	int b[] = {1, 1, 1, 1, 1};

	foo(a, b, 5);

	for (int i = 0; i < 5; ++i)
		cout << b[i] << '\t';
	cout << endl;
}

void foo(int *p_a_, int *p_b_, int n_) {
	p_b_[0] = 1;
	int i;

	for (i = 1; i < n_; ++i) {
		p_b_[i] = p_b_[i - 1] * p_a_[i - 1];
	}
	for (i = n_ - 2; i >= 0; --i) {
		p_a_[i] *= p_a_[i + 1];
	}
	for (i = 0; i < n_ - 1; ++i) {
		p_b_[i] *= p_a_[i + 1];
	}
}