A

http://codeforces.com/contest/560/problem/A

推断给出的数能否组成全部自然数。

水题

int a[1010];

bool b[1000010];

int main()

{

    int n;

    while (scanf("%d", &n) != EOF)

    {

        memset(b,false,sizeof(b));

        for (int i = 1; i <= n; i++)

        {

            scanf("%d", &a[i]);

            b[a[i]] = true;

        }

        int ans = 0;

        if (b[1] == false) ans = 1;

        else if (b[1]) ans = -1;

        printf("%d\n",ans);

    }

    return 0;

}

B

http://codeforces.com/contest/560/problem/B

推断一个矩形能否装下另外两个矩形

int a1, a2, a3, b1, b2, b3;

int main()

{

    while (scanf("%d%d%d%d%d%d", &a1, &b1, &a2, &b2, &a3, &b3) != EOF)

    {

        int ok = 0;

        int t1 = max(b2, b3);

        int r1 = max(a2, a3);

        if ((t1 <= a1 && (a2 + a3) <= b1)) ok = 1;

        if ((t1 <= b1 && (a2 + a3) <= a1)) ok = 1;

        if ((r1 <= a1 && (b2 + b3) <= b1)) ok = 1;

        if ((r1 <= b1 && (b2 + b3) <= a1)) ok = 1;

        int t11 = max(b2, a3);

        int r11 = max(a2, b3);

        if ((r11 <= a1 && (b2 + a3) <= b1)) ok = 1;

        if ((r11 <= b1 && (b2 + a3) <= a1)) ok = 1;

        if ((t11 <= a1 && (a2 + b3) <= b1)) ok = 1;

        if ((t11 <= b1 && (a2 + b3) <= a1)) ok = 1;

        if (ok) puts("YES");

        else puts("NO");

    }

    return 0;

}

C

http://codeforces.com/contest/560/problem/C

推断组成六边形须要的三角形个数

int a, b, c, d, e, f;

int main()

{

    while (scanf("%d%d%d%d%d%d", &a, &b, &c, &d, &e, &f) != EOF)

    {

        printf("%d\n", (a + b + c)*(a + b + c) - (a*a + c*c + e*e));

    }

    return 0;

}