leetcode_238_1.java

public int[] productExceptSelf(int[] nums) {
    int n = nums.length;
    int[] pre = new int[n];
    for(int i = 0 ; i < n ; i++){
        pre[i] = (i == 0) ? 1 : pre[i-1] * nums[i - 1];
    }

    int post = 1 ;
    int[] res = new int[n];
    for(int i = n-1 ; i >= 0 ; i--){
        res[i] = post * pre[i];
        post *= nums[i];
    }
    return res;
}