제출 #1321991

#제출 시각아이디문제언어결과실행 시간메모리
1321991jmuzhen모자이크 (IOI24_mosaic)C++20
20 / 100
92 ms20724 KiB
#include <vector>
#include <algorithm>
#include <iostream>

using namespace std;

// We use long long for sums to avoid overflow (N*N can be 4*10^10)
typedef long long ll;

struct GridSolver {
    int N;
    // Prefix sums for the diagonal values
    // S0[k] = sum of V[i] for i <= k
    // S1[k] = sum of i * V[i] for i <= k
    // Indices for V range from -(N-1) to (N-1).
    // We offset them by adding N.
    vector<ll> S0, S1;
    
    // Prefix sums for Row 0 and Col 0
    vector<int> PX, PY;

    void build(int n, const vector<int>& X, const vector<int>& Y) {
        N = n;
        
        // 1. Compute Row 1 and Col 1 values (for the grid starting at 1,1)
        // Global (1, j) depends on Global (0, j) and Global (1, j-1)
        // Global (i, 1) depends on Global (i-1, 1) and Global (i, 0)
        
        vector<int> R1(N), C1(N);
        
        // Compute (1, 1)
        int val_1_1 = ((X[1] == 0) && (Y[1] == 0)) ? 1 : 0;
        R1[1] = val_1_1;
        C1[1] = val_1_1;
        
        for (int j = 2; j < N; ++j) {
            R1[j] = ((X[j] == 0) && (R1[j-1] == 0)) ? 1 : 0;
        }
        for (int i = 2; i < N; ++i) {
            C1[i] = ((C1[i-1] == 0) && (Y[i] == 0)) ? 1 : 0;
        }
        
        // 2. Build V array
        // V[k] corresponds to diagonal c - r = k
        // range of k: -(N-1) to (N-1)
        // Size needed: 2*N
        int offset = N;
        int v_size = 2 * N + 5;
        vector<int> V(v_size, 0);
        
        // Center k=0 is (1,1) -> R1[1]
        V[0 + offset] = R1[1];
        
        // Positive k: (1, 1+k) -> R1[1+k]
        for (int k = 1; k < N; ++k) {
            if (1 + k < N) V[k + offset] = R1[1+k];
        }
        
        // Negative k: (1-k, 1) -> C1[1-k]. Let k = -d. (1+d, 1) -> C1[1+d]
        for (int k = -1; k > -N; --k) {
            if (1 - k < N) V[k + offset] = C1[1-k];
        }
        
        // 3. Build Prefix Sums
        S0.assign(v_size, 0);
        S1.assign(v_size, 0);
        
        for (int i = 0; i < v_size; ++i) {
            ll val = V[i];
            ll prev0 = (i > 0) ? S0[i-1] : 0;
            ll prev1 = (i > 0) ? S1[i-1] : 0;
            // The actual k value is (i - offset)
            ll k = i - offset;
            
            S0[i] = prev0 + val;
            S1[i] = prev1 + k * val;
        }
        
        // 4. Prefix sums for X and Y
        PX.assign(N, 0);
        PY.assign(N, 0);
        PX[0] = X[0];
        for(int i=1; i<N; ++i) PX[i] = PX[i-1] + X[i];
        PY[0] = Y[0];
        for(int i=1; i<N; ++i) PY[i] = PY[i-1] + Y[i];
    }
    
    ll get_S0(int k1, int k2) {
        int offset = N;
        int i1 = k1 + offset;
        int i2 = k2 + offset;
        if (i1 > i2) return 0;
        // Clamp indices just in case, though logic should prevent OOB
        i1 = max(0, i1);
        i2 = min((int)S0.size()-1, i2);
        
        ll v2 = S0[i2];
        ll v1 = (i1 > 0) ? S0[i1-1] : 0;
        return v2 - v1;
    }

    ll get_S1(int k1, int k2) {
        int offset = N;
        int i1 = k1 + offset;
        int i2 = k2 + offset;
        if (i1 > i2) return 0;
        i1 = max(0, i1);
        i2 = min((int)S1.size()-1, i2);
        
        ll v2 = S1[i2];
        ll v1 = (i1 > 0) ? S1[i1-1] : 0;
        return v2 - v1;
    }
    
    // Calculate sum of diagonals in global rect [1..rows] x [1..cols]
    // Note: rows, cols are counts.
    // e.g. rows=2 means global rows 1 and 2 are included.
    ll calc_grid_sum(int rows, int cols) {
        if (rows <= 0 || cols <= 0) return 0;
        
        ll total = 0;
        
        if (rows <= cols) {
            // Zone 1: [1-rows, 0]. Count = rows + k
            total += (ll)rows * get_S0(1-rows, 0) + get_S1(1-rows, 0);
            
            // Zone 2: [1, cols-rows]. Count = rows
            total += (ll)rows * get_S0(1, cols-rows);
            
            // Zone 3: [cols-rows+1, cols-1]. Count = cols - k
            total += (ll)cols * get_S0(cols-rows+1, cols-1) - get_S1(cols-rows+1, cols-1);
        } else {
            // Zone 1: [1-rows, cols-rows]. Count = rows + k
            total += (ll)rows * get_S0(1-rows, cols-rows) + get_S1(1-rows, cols-rows);
            
            // Zone 2: [cols-rows+1, 0]. Count = cols
            total += (ll)cols * get_S0(cols-rows+1, 0);
            
            // Zone 3: [1, cols-1]. Count = cols - k
            total += (ll)cols * get_S0(1, cols-1) - get_S1(1, cols-1);
        }
        
        return total;
    }
    
    ll query_X(int L, int R) {
        if (L > R) return 0;
        ll v2 = PX[R];
        ll v1 = (L > 0) ? PX[L-1] : 0;
        return v2 - v1;
    }
    
    ll query_Y(int T, int B) {
        if (T > B) return 0;
        ll v2 = PY[B];
        ll v1 = (T > 0) ? PY[T-1] : 0;
        return v2 - v1;
    }
};

vector<long long> mosaic(vector<int> X, vector<int> Y, vector<int> T, vector<int> B, vector<int> L, vector<int> R) {
    int N = X.size();
    int Q = T.size();
    
    GridSolver solver;
    solver.build(N, X, Y);
    
    vector<long long> results(Q);
    
    for (int k = 0; k < Q; ++k) {
        int t = T[k];
        int b = B[k];
        int l = L[k];
        int r = R[k];
        
        ll ans = 0;
        
        // Part A: Row 0
        if (t == 0) {
            ans += solver.query_X(l, r);
        }
        
        // Part B: Col 0 (excluding (0,0) if already counted)
        if (l == 0) {
            // If we counted row 0, we counted (0,0). So start from row 1.
            // But query range for Y is [t, b].
            // Intersection of [t, b] and [1, N-1].
            int y_start = max(1, t);
            if (y_start <= b) {
                ans += solver.query_Y(y_start, b);
            }
        }
        
        // Part C: Grid [1..N-1] x [1..N-1]
        // Intersection of query [t, b] x [l, r] with [1, N-1] x [1, N-1]
        int t_prime = max(1, t);
        int l_prime = max(1, l);
        
        if (t_prime <= b && l_prime <= r) {
            // We need sum in [t_prime, b] x [l_prime, r]
            // Maps to calc_grid_sum args: calc(row_idx, col_idx)
            // Indices in calc are inclusive max row/col
            // Global row index i maps to calc arg i.
            
            ans += solver.calc_grid_sum(b, r)
                 - solver.calc_grid_sum(t_prime - 1, r)
                 - solver.calc_grid_sum(b, l_prime - 1)
                 + solver.calc_grid_sum(t_prime - 1, l_prime - 1);
        }
        
        results[k] = ans;
    }
    
    return results;
}
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