HDU 5055 Bob and math problem(简单贪心)

http://acm.hdu.edu.cn/showproblem.php?pid=5055

题目大意:

  给你N位数,每位数是0~9之间。你把这N位数构成一个整数。

要求:

  1、必须是奇数

  2、整数的前面没有0

  3、找到一个最大的整数

如果满足1、2、3条件,就输出这个数,不满足就输出-1.

给个例子

3

1 0 0

这个构成的奇数是001,这个数前面有0,应该输出-1

解题思路:

  对给的N个数升序排序。

  然后最小的开始找,找到一个奇数,然后把它放在最左边。

  然后判断这个数是否,满足要求。满足要求,就输出。不满足就输出-1

AC代码:

 1 #include<cstdio>
 2 #include<algorithm>
 3 using namespace std;
 4
 5 #define MAXN 110
 6
 7 int main(){
 8     int i, j, n, digit[MAXN];
 9     while(~scanf("%d", &n)){
10         for(i = 0; i < n; ++i){
11             scanf("%d", &digit[i]);
12         }
13
14         sort(digit, digit + n);//升序
15
16         for(i = 0; i < n; ++i){//从左边开始找,找出一个奇数
17             if(digit[i] & 1){//if(digit[i] % 2 == 1)
18                 int t = digit[i];
19                 for(j = i; j > 0; --j){//将所有的数往右移一位
20                     digit[j] = digit[j - 1];
21                 }
22                 digit[j] = t;//把找到的奇数放在最后一位
23                 break;//找到了 就跳出循环
24             }
25         }
26
27         if(digit[n - 1] && i < n){//这个整数没有前导0,并且在这个大数是奇数
28             for(j = n - 1; j > 0; --j)
29                 printf("%d", digit[j]);
30             printf("%d\n", digit[j]);
31         }else{
32             puts("-1");
33         }
34
35     }
36     return 0;
37 }
时间: 2024-10-06 22:56:44

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