位操作(求[a, b] 中二进制位为1的个数最多的数)

 1 #include <stdio.h>
 2 
 3 typedef long long ll;
 4 
 5 int main(void) {
 6     int n;
 7     scanf("%d", &n);
 8     while (n-- > 0) {
 9         ll l, r;
10         scanf("%lld %lld", &l, &r);
11 
12         ll res = l;
13         while ((res|(res+1)) <= r) {
14             res |= res + 1; // set the lowest 0
15         }
16         printf("%lld\n", res);
17     }
18 
19     return 0;
20 }