代码

#include <unordered_map>
#include <arpa/inet.h>
#include "router.h"

std::unordered_map<unsigned, unsigned> M[256][33];

void ins(const RoutingTableEntry *e) {
	M[e->addr&255][e->len][htonl(e->addr)] = e->nexthop;
}

void init(int n, int q, const RoutingTableEntry *tbl) {
	for (int i = 0; i < n; i++) {
		ins(tbl + i);
	}
}

unsigned query(unsigned addr) {unsigned char bb=addr;
	addr = htonl(addr); 
	
	for (int i = 32; i >= 0; i--) {
		if (M[bb][i].count(addr) > 0) {
			return M[bb][i][addr];
		}
		addr &= ~(1u << (32 - i));
	}
	
	return 0;
}

评测结果