CF169D2 D – Little Girl and Maximum XOR 贪心

解题思路:

经过打表可得规律答案要么是0 要么是2的N次

要得到最大的XOR值,其值一定是2的N次

即在 l 和 r 的二进制中,从左到右遍历过去,如果碰到 l 为 1 r 为
0

则可说明在『l , r】中存在 1000000000 和 0111111111
可得到最大XOR值为2的N次

PS:不会存在首先出现 l 为 0 r 为 1 的情况,因为 l <
r


#include<stdio.h>
#include<math.h>
int main(){
long long x,y,ans=0;
int i;
while(EOF != scanf("%lld%lld",&x,&y)){
ans = 0;
for(i=63;i>=0;i--)
if((x&((long long)1<<i))^(y&((long long)1<<i))) break;
ans = pow(2,i+1)-1;
printf("%lld\n",ans);
}
return 0;
}

题目描述

A little girl loves problems on bitwise operations very much. Here‘s one of
them.

You are given two integers l and r. Let‘s consider the values of  for
all pairs of integers a and b (l?≤?a?≤?b?≤?r).
Your task is to find the maximum value among all considered ones.

Expression  means
applying bitwise excluding or operation to integers x and y. The given operation exists in all modern
programming languages, for example, in languages C++ and Java it is represented as "^",
in Pascal — as ?xor?.

输入

The input consists of multiple test cases.

Each test case contains space-separated integers l and r (1?≤?l?≤?r?≤?1018).

输出

In a single line print a single integer — the maximum value of  for
all pairs of integers ab (l?≤?a?≤?b?≤?r).

---恢复内容结束---

题目描述

A little girl loves problems on bitwise operations very much. Here‘s one of
them.

You are given two integers l and r. Let‘s consider the values of  for
all pairs of integers a and b (l?≤?a?≤?b?≤?r).
Your task is to find the maximum value among all considered ones.

Expression  means
applying bitwise excluding or operation to integers x and y. The given operation exists in all modern
programming languages, for example, in languages C++ and Java it is represented as "^",
in Pascal — as ?xor?.

输入

The input consists of multiple test cases.

Each test case contains space-separated integers l and r (1?≤?l?≤?r?≤?1018).

输出

In a single line print a single integer — the maximum value of  for
all pairs of integers ab (l?≤?a?≤?b?≤?r).

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时间: 2024-10-26 20:13:56

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