代码

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

std::map<unsigned, unsigned> M[33];

void ins(const RoutingTableEntry *e) {
    M[e->len][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 addr0=addr;
    addr = htonl(addr);

    for (int i = 32; i >= 0; i--) {
        if (M[i].count(addr0) > 0) {
            return M[i][addr0];
        }
        addr &= ~(1u << (32 - i));
        addr0&=~(1u<<((i-1)/8*8+7-(i-1)%8));
        addr=htonl(addr0);
    }

    return 0;
}

评测结果