leetcode-go/poj/2799.ip-networks/main.cc

#include <cstdio>
#include <cstdlib>

const int M = 1000;

char buf[16];

int mask[] = {1 << 7, 1 << 6, 1 << 5, 1 << 4, 1 << 3, 1 << 2, 1 << 1, 1};

void itob(int i, bool *b) {
    for (int j = 0; j < 8; j++) {
        b[j] = i & mask[j];
    }
}

int btoi(bool *b) {
    int i = 0;
    for (int j = 0; j < 8; j++) {
        if (b[j]) i += mask[j];
    }
    return i;
}

bool ip[M][32];

void print_ip(int m) {
    for (int i = 0; i < m; i++) {
        for (int j = 0; j < 32; j++) {
            printf("%d", ip[i][j]);
        }
        printf("\n");
    }
}

int main() {
    int m;
    scanf("%d\n", &m);
    for (int i = 0; i < m; i++) {
        scanf("%s\n", buf);
        for (int pre = 0, cur = 0, j = 0; j < 4; j++) {
            while (buf[cur] != '.' && buf[cur] != 0) cur++;
            buf[cur] = 0;
            int num = atoi(buf + pre);
            itob(num, ip[i] + 8 * j);
            cur++;
            pre = cur;
        }
    }
    int i;
    for (i = 0; i < 32; i++) {
        bool flag = ip[0][i];
        for (int j = 0; j < m; j++) {
            if (ip[j][i] != flag) goto end;
        }
    }
end:
    for (int j = i; j < 32; j++) {
        ip[0][j] = false;
    }
    printf("%d.%d.%d.%d\n", btoi(ip[0]), btoi(ip[0] + 8), btoi(ip[0] + 16), btoi(ip[0] + 24));
    for (int j = 0; j < i; j++) {
        ip[0][j] = true;
    }
    printf("%d.%d.%d.%d\n", btoi(ip[0]), btoi(ip[0] + 8), btoi(ip[0] + 16), btoi(ip[0] + 24));
    return 0;
}