代码

#pragma GCC optimize("Ofast")
#include"router.h"
#include<unordered_map>
std::unordered_map<unsigned,unsigned>a[33];
void init(int b,int,const RoutingTableEntry*c){for(int d=0;d<b;d++)a[c[d].len][c[d].addr]=c[d].nexthop;}
unsigned query(unsigned b){for(int c=32;c;c--,b&=~(1u<<(c>>3<<3|~c&7)))if(auto d=a[c].find(b);d!=a[c].end())return d->second;return 0;}

评测结果