代码

#include "router.h"
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <map>
#include <arpa/inet.h>
using namespace std;

map<pair<unsigned, char>, unsigned> table;

void init(int n, int q, const RoutingTableEntry *a) {
	for (int i=0; i<n; i++) {
        RoutingTableEntry x = a[i];
        x.addr = htonl(x.addr);
        x.len = 32 - x.len;
        if (x.len != 32) {
            unsigned mask = (-1)^((1<<x.len)-1);
            x.addr &= mask; 
        } else {
            x.addr = 0;
        }
        pair<unsigned, char> pr = make_pair((unsigned)x.addr, x.len);
        if (table.find(pr) == table.end())
            table[pr] = x.nexthop;
    }
}

unsigned query(unsigned addr) {
    addr = htonl(addr);
    for (char i = 0; i <= 32; i++)
    {
        if (i != 32) {
            unsigned mask = (-1)^((1<<i)-1);
            addr &= mask;
        } else {
            addr = 0;
        }
        pair<unsigned, char> toSearch = make_pair(addr, i);
        if (table.find(toSearch) != table.end()) {
            return table[toSearch];
        }
    }
	return 0;
}

评测结果