题目链接：http://acm.nyist.edu.cn/JudgeOnline/problem.php?pid=412
Same binary weight
时间限制：300 ms | 内存限制：65535 KB
难度：3
- 描述
-
The binary weight of a positive integer is the number of 1‘s in its binary representation.for example,the decmialnumber 1 has a binary weight of 1,and the decimal number 1717 (which is 11010110101 in binary) has a binary weight
of 7.Give a positive integer N,return the smallest integer greater than N that has the same binary weight as N.N will
be between 1 and 1000000000,inclusive,the result is guaranteed to fit in a signed 32-bit interget.
- 输入
- The input has multicases and each case contains a integer N.
- 输出
- For each case,output the smallest integer greater than N that has the same binary weight as N.
- 样例输入
-
1717 4 7 12 555555
- 样例输出
-
1718 8 11 17 555557
看到问题后没有任何思路，在查看讨论区以后发现是使用STL中的bitset来解决的
大体看完了bitset的用法
或许暴力的方法是可行的，每次+1逐一尝试
1 #define _CRT_SBCURE_NO_DEPRECATE
2 #include <bitset>
3 #include <cstdio>
4 #include <cstring>
5 #include <iostream>
6
7 using namespace std;
8
9 int main()
10 {
11 int n;
12 while(scanf("%d",&n)!=EOF)
13 {
14 bitset<32> b(n);
15 int nlen = b.count();
16 int ilen;
17 for(int i = n+1;;i++)
18 {
19 bitset<32> bb(i);
20 ilen = bb.count();
21 if(nlen == ilen)
22 {
23 cout << i << endl;
24 break;
25 }
26 }
27 }
28
29 return 0;
30 }
但是提交后超时了，看来需要找更快的方法，看完别人的题解后来自己找一下规律解决问题
将十进制转化为二进制
4 :00000100
8 :00001000
7 :00000111
11:00001011
12:00001100
17:00010001
1717:0011010110101
1718:0011010110110
1.从右到左发现的第一个01都变成了10
2.发现的第一个01的左边是没有变化的
3.01右边的1都移动到了最右边
（其实我也不知道怎么发现的这么神奇的规律 emmmm...）
一道比较神奇的题目
接下来的工作就简单些了，根据发现的规律来实现代码
#define _CRT_SBCURE_NO_DEPRECATE
#include <bitset>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
using namespace std;
int main()
{
int n;
while(scanf("%d",&n)!=EOF)
{
bitset<32> b(n);
int i,coun = 0;
for(i = 0;i < 32;i++)
{
if(b[i] == 1)
coun++;
if(b[i] == 1 && b[i+1] == 0)
{
b[i] = 0;
b[i+1] = 1;
break;
}
}
int j = i-1;
for(int i = 0;i <= j;i++)
{
if(i < coun-1)
b[i] = 1;
else
b[i] = 0;
}
cout << b.to_ulong() << endl;
}
return 0;
}
原文地址：https://www.cnblogs.com/duny31030/p/8830762.html