Submission #92376

#	Time	Username	Problem	Language	Result	Execution time	Memory
92376		Alexa2001	Snake Escaping (JOI18_snake_escaping)	C++17	100 / 100	1048 ms	47284 KiB

snake_escaping

#include <bits/stdc++.h>

using namespace std;

const int Nmax = (1<<20);

int n, q;
char S[Nmax+2], Val[Nmax+2];
int val[Nmax], up[Nmax], down[Nmax], bits[Nmax];

void precalc()
{
    int i, j;
    for(i=0; i<(1<<n); ++i)
        bits[i] = __builtin_popcount(i), up[i] = down[i] = val[i] = Val[i] - '0';

    for(i=0; i<n; ++i)
        for(j=0; j<(1<<n); ++j)
            if(j & (1<<i))
                up[j ^ (1<<i)] += up[j];
            else down[j ^ (1<<i)] += down[j];
}

int solveQ(int mask, int que)
{
    int i, j, ans = 0;
    for(i=que, j = 0; j < (1<<bits[que]); i = (i-1) & que, ++j)
        ans += val[i ^ mask];
    return ans;
}

int solve0(int mask0, int mask1)
{
    int i, j, ans = 0;
    for(i=mask0, j = 0; j < (1<<bits[mask0]); i = (i-1) & mask0, ++j)
        if(bits[i] & 1) ans -= up[mask1 ^ i];
            else ans += up[mask1 ^ i];
    return ans;
}

int solve1(int mask1, int maskq)
{
    int i, j, ans = 0;
    for(i=mask1, j = 0; j < (1<<bits[mask1]); i = (i-1) & mask1, ++j)
        if(bits[i] & 1) ans -= down[maskq ^ mask1 ^ i];
            else ans += down[maskq ^ mask1 ^ i];
    return ans;
}

int query()
{
    scanf("%s\n", S);
    reverse(S, S + n);

    int i, mask0 = 0, mask1 = 0, maskq = 0;
    for(i=0; i<n; ++i)
    {
        if(S[i] == '0') mask0 ^= (1<<i);
            else if(S[i] == '1') mask1 ^= (1<<i);
                else maskq ^= (1<<i);
    }

    if(bits[maskq] <= bits[mask0] && bits[maskq] <= bits[mask1]) return solveQ(mask1, maskq);
    else if(bits[mask0] <= bits[mask1]) return solve0(mask0, mask1);
        else return solve1(mask1, maskq);
}

int main()
{
   // freopen("input", "r", stdin);
    cin.sync_with_stdio(false);

    scanf("%d %d\n", &n, &q);
    scanf("%s\n", Val);

    precalc();
    while(q--)
        cout << query() << '\n';

    return 0;
}

Compilation message (stderr)

snake_escaping.cpp: In function 'int query()':
snake_escaping.cpp:52:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s\n", S);
     ~~~~~^~~~~~~~~~~
snake_escaping.cpp: In function 'int main()':
snake_escaping.cpp:73:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d\n", &n, &q);
     ~~~~~^~~~~~~~~~~~~~~~~~~
snake_escaping.cpp:74:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s\n", Val);
     ~~~~~^~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 10 / 10
• Subtask 4: 53 / 53
• Subtask 5: 25 / 25