Submission #452107

#	Time	Username	Problem	Language	Result	Execution time	Memory
452107		dxz05	Bomb (IZhO17_bomb)	C++14	35 / 100	1103 ms	55916 KiB

bomb

#pragma GCC optimize("Ofast,O2,O3")
#pragma GCC target("avx2")

#include <bits/stdc++.h>

using namespace std;

void debug_out() { cerr << endl; }

template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << "[" << H << "]";
    debug_out(T...);
}

#ifdef dddxxz
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

#define SZ(s) ((int)s.size())
#define all(x) (x).begin(), (x).end()
#define revall(x) (x).rbegin(), (x).rend()

clock_t startTime;

double getCurrentTime() {
    return (double) (clock() - startTime) / CLOCKS_PER_SEC;
}

#define MP make_pair

typedef long long ll;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
const double eps = 0.00001;
const int MOD = 1e9;
const int INF = 1000000101;
const long long LLINF = 1223372000000000555;
const int N = 2e6 + 3e2;
const int M = 2522;

int n, m;
int a[M][M];
bool bomb[M][M];
int dp[M][M];

int sum(int x1, int y1, int x2, int y2){
    assert(x1 <= x2 && y1 <= y2);
    int res = dp[x2][y2];
    res -= dp[x1 - 1][y2];
    res -= dp[x2][y1 - 1];
    res += dp[x1 - 1][y1 - 1];
    return res;
}

int ans = 0;

bool check(int A, int B){
    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= m; j++) bomb[i][j] = false;
    }

    for (int i = 1; i <= n - A + 1; i++){
        for (int j = 1; j <= m - B + 1; j++){
            if (!a[i][j]) continue;
            if (sum(i, j, i + A - 1, j + B - 1) == A * B){
                for (int x = i; x <= i + A - 1; x++){
                    for (int y = j; y <= j + B - 1; y++){
                        bomb[x][y] = true;
                    }
                }
            }
        }
    }

//    for (int i = n; i >= A; i--){
//        for (int j = m; j >= B; j--){
//            if (!a[i][j]) continue;
//            if (sum(i - A + 1, j - B + 1, i, j) == A * B){
//                for (int x = i - A + 1; x <= i; x++){
//                    for (int y = j - B + 1; y <= j; y++){
//                        bomb[x][y] = true;
//                    }
//                }
//            }
//        }
//    }

    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= m; j++){
            if (!bomb[i][j] && a[i][j]) return false;
        }
    }

    ans = max(ans, A * B);

    return true;
}

void solve(int TC) {
    cin >> n >> m;

    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= m; j++){
            char ch;
            cin >> ch;
            a[i][j] = ch - '0';
            dp[i][j] = dp[i][j - 1] + a[i][j];
        }
    }

    for (int j = 1; j <= m; j++){
        for (int i = 1; i <= n; i++){
            dp[i][j] += dp[i - 1][j];
        }
    }

    if (n < m){
        for (int i = 1; i <= n; i++){
            int l = 1, r = m;
            while (l <= r){
                int mid = (l + r) >> 1;
                if (check(i, mid)){
                    l = mid + 1;
                } else r = mid - 1;
            }
        }
    } else {
        for (int i = 1; i <= m; i++){
            int l = 1, r = n;
            while (l <= r){
                int mid = (l + r) >> 1;
                if (check(mid, i)){
                    l = mid + 1;
                } else r = mid - 1;
            }
        }
    }

    cout << ans;

}

int main() {
    startTime = clock();
    cin.tie(nullptr);
    cout.tie(nullptr);
    ios_base::sync_with_stdio(false);

    bool llololcal = false;
#ifdef dddxxz
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    llololcal = true;
#endif

    int TC = 1;
    //cin >> TC;

    for (int test = 1; test <= TC; test++) {
        debug(test);
        //cout << "Case #" << test << ": ";
        solve(test);
    }

    if (llololcal) cerr << endl << "Time: " << int(getCurrentTime() * 1000) << " ms" << endl;

    return 0;
}

Compilation message (stderr)

bomb.cpp: In function 'int main()':
bomb.cpp:19:20: warning: statement has no effect [-Wunused-value]
   19 | #define debug(...) 42
      |                    ^~
bomb.cpp:162:9: note: in expansion of macro 'debug'
  162 |         debug(test);
      |         ^~~~~

• Subtask 1: 35 / 100