Submission #1292273

#	Time	Username	Problem	Language	Result	Execution time	Memory
1292273		wedonttalkanymore	Lamps (JOI19_lamps)	C++20	100 / 100	35 ms	49464 KiB

lamp

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

#define int long long
#define pii pair<ll, ll>
#define fi first
#define se second

const ll N = 1e6 + 5, inf = 1e18, mod = 1e9 + 7, block = 320, lim = 19;

int n;
string A, B;
int a[N], b[N];
int dp[N][4];

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    if (fopen(".inp", "r")) {
        freopen(".inp", "r", stdin);
        freopen(".out", "w", stdout);
    }
    cin >> n >> A >> B;
    for (int i = 0; i < n; i++) {
        a[i + 1] = A[i] - '0';
        b[i + 1] = B[i] - '0';
    }
    dp[1][0] = 1 + ((0 ^ b[1]) == 1);
    dp[1][1] = 1 + ((1 ^ b[1]) == 1);
    dp[1][2] = ((a[1] ^ b[1]) == 1);
    for (int i = 2; i <= n; i++) {
        // off
        dp[i][0] = dp[i][1] = dp[i][2] = inf;
        dp[i][0] = min(dp[i][0], dp[i - 1][0] + (b[i] == 1 && b[i - 1] == 0));
        dp[i][0] = min(dp[i][0], dp[i - 1][1] + (b[i] == 1 && b[i - 1] == 1) + 1);
        dp[i][0] = min(dp[i][0], dp[i - 1][2] + (b[i] == 1 && (a[i - 1] ^ b[i - 1]) == 0) + 1);
        // on
        dp[i][1] = min(dp[i][1], dp[i - 1][0] + (b[i] == 0 && b[i - 1] == 0) + 1);
        dp[i][1] = min(dp[i][1], dp[i - 1][1] + (b[i] == 0 && b[i - 1] == 1));
        dp[i][1] = min(dp[i][1], dp[i - 1][2] + (b[i] == 0 && (a[i - 1] ^ b[i - 1]) == 0) + 1);
        // flip
        dp[i][2] = min(dp[i][2], dp[i - 1][0] + ((a[i] ^ b[i]) == 1 && b[i - 1] == 0));
        dp[i][2] = min(dp[i][2], dp[i - 1][1] + ((a[i] ^ b[i]) == 1 && b[i - 1] == 1));
        dp[i][2] = min(dp[i][2], dp[i - 1][2] + ((a[i] ^ b[i]) == 1 && (a[i - 1] ^ b[i - 1]) == 0));
    }
    cout << min({dp[n][0], dp[n][1], dp[n][2]});
    return 0;
}

Compilation message (stderr)

lamp.cpp: In function 'int main()':
lamp.cpp:22:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
lamp.cpp:23:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |         freopen(".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 41 / 41
• Subtask 3: 4 / 4
• Subtask 4: 49 / 49