Submission #201034

#	Time	Username	Problem	Language	Result	Execution time	Memory
201034		HellAngel	JJOOII 2 (JOI20_ho_t2)	C++14	100 / 100	94 ms	48516 KiB

ho_t2

#include <bits/stdc++.h>

using namespace std;

const int maxn = 200007;
string s;
int nxt[20][maxn][3], a[maxn], n, k, ans;

void Jump(int &pos, int type, int cnt)
{
    for(int i = 19; i >= 0; i--)
    {
        if(cnt >= (1 << i))
        {
            cnt -= (1 << i);
            pos = nxt[i][pos][type];
        }
    }
}

int32_t main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if(fopen("test.inp", "r")) freopen("test.inp", "r", stdin);
    cin >> n >> k >> s;
    ans = n + 1;
    for(int i = 1; i <= n; i++)
    {
        if(s[i - 1] == 'J') a[i] = 0;
        if(s[i - 1] == 'O') a[i] = 1;
        if(s[i - 1] == 'I') a[i] = 2;
    }
    nxt[0][n + 1][0] = nxt[0][n + 1][1] = nxt[0][n + 1][2] = n + 1; 
    for(int i = n; i >= 1; i--)
    {
        for(int j = 0; j < 3; j++) nxt[0][i][j] = nxt[0][i + 1][j]; 
        if(i == n) continue;
        nxt[0][i][a[i + 1]] = i + 1;
    }
    for(int len = 1; len < 20; len++)
    {
        for(int i = 1; i <= n + 1; i++)
        {
            for(int j = 0; j < 3; j++)
            {
                int nlen = (1 << len);
                if(i + nlen - 1 > n) nxt[len][i][j] = 1 + n;
                nxt[len][i][j] = nxt[len - 1][nxt[len - 1][i][j]][j];
            }
        }
    }
    for(int i = 1; i <= n; i++)
    {
        int cur = i;
        if(a[cur] != 0) continue;
        Jump(cur, 0, k - 1);
        Jump(cur, 1, k);
        Jump(cur, 2, k);
        if(cur <= n)
        {
            ans = min(ans, cur - i + 1 - k * 3);
        }
    }
    if(ans == n + 1) cout << -1;
    else cout << ans;
}

Compilation message (stderr)

ho_t2.cpp: In function 'int32_t main()':
ho_t2.cpp:25:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
     if(fopen("test.inp", "r")) freopen("test.inp", "r", stdin);
                                ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 1 / 1
• Subtask 2: 12 / 12
• Subtask 3: 87 / 87