Today, Wet Shark is given n integers. Using any of these integers no more than once, Wet Shark wants to get maximum possible even (divisible by 2) sum. Please, calculate this value for Wet Shark.
Note, that if Wet Shark uses no integers from the n integers, the sum is an even integer 0.
The first line of the input contains one integer, n (1 ≤ n ≤ 100 000). The next line contains n space separated integers given to Wet Shark. Each of these integers is in range from 1 to 109, inclusive.
Print the maximum possible even sum that can be obtained if we use some of the given integers.
3
1 2 3
6
5
999999999 999999999 999999999 999999999 999999999
3999999996
In the first sample, we can simply take all three integers for a total sum of 6.
In the second sample Wet Shark should take any four out of five integers 999 999 999.
题意:给出n个数,求取任意个数相加的和且是偶数,最大是多少?
题解:把n个数相加得sum,统计奇数的个数,个数为奇数,sum减去最小的奇数就好了。
代码如下:
#include<cstdio> #define LL __int64 #define INF 1111111111 LL a; int main() { int n,i,j,cnt; LL min,sum; while(scanf("%d",&n)!=EOF) { sum=0; cnt=0; min=INF; for(i=0;i<n;++i) { scanf("%I64d",&a); if(a&1) { cnt++; if(a<min) min=a; } sum+=a; } if(cnt>0&&cnt&1) printf("%I64d\n",sum-min); else printf("%I64d\n",sum); } return 0; }