A. Memory and Crow time limit per test:2 seconds memory limit per test:256 megabytes input:standard input output:standard output
There arenintegersb1, b2, ..., bnwritten in a row. For allifrom 1 to n, valuesaiare defined by the crows performing the following procedure:
The crow setsaiinitially 0. The crow then addsbitoai, subtractsbi + 1, adds thebi + 2 number, and so on until then'th number. Thus,ai = bi - bi + 1 + bi + 2 - bi + 3.... Memory gives you the valuesa1, a2, ..., an, and he now wants you to find the initial numbersb1, b2, ..., bnwritten in the row? Can you do it? Input The first line of the input contains a single integern(2 ≤ n ≤ 100 000)— the number of integers written in the row. The next line containsn, the i'th of which isai( - 109 ≤ ai ≤ 109)— the value of thei'th number. Output Printnintegers corresponding to the sequenceb1, b2, ..., bn. It's guaranteed that the answer is unique and fits in 32-bit integer type. Examples Input 5 6 -4 8 -2 3 Output 2 4 6 1 3 Input 5 3 -2 -1 5 6 Output 1 -3 4 11 6 Note In the first sample test, the crows report the numbers 6, - 4, 8, - 2, and 3 when he starts at indices 1, 2, 3, 4 and 5 respectively. It is easy to check that the sequence 2 4 6 1 3 satisfies the reports. For example, 6 = 2 - 4 + 6 - 1 + 3, and - 4 = 4 - 6 + 1 - 3. In the second sample test, the sequence 1, - 3, 4, 11, 6 satisfies the reports. For example, 5 = 11 - 6 and 6 = 6. 解题思路: 【题意】 有n个数b1, b2, ..., bn a1, a2, ..., an是通过等式ai = bi - bi + 1 + bi + 2 - bi + 3....(±)bn得到的 现给你a1, a2, ..., an这n个数,问b1, b2, ..., bn是多少 【类型】 公式推导 【分析】 由此可见,数组b中的第i项等于数组a中的第i项与第i+1项之和 特别地,数组b中的第n项等于数组a中的第n项 【时间复杂度&&优化】 O(n) 题目链接→Codeforces Problem 712A Memory and Crow 1 #include <bits/stdc++.h> 2 using namespace std; 3 int main() 4 { 5int n,a,b; 6while(cin>>n) 7{ 8 for(int i=1;i<=n;i++) 9 {10 cin>>a;11 if(i>1)12 cout<<a+b<<" ";13 b=a;14 }15 cout<<a<<endl;16}17return 0;18 }
