UVa572

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題目:
https://onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=513

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

char mp[105][105] = {};
bool passed[105][105] = {false};
int row, col;

int dx[] = {0, 1, 1, 1, 0, -1, -1, -1};
int dy[] = {1, 1, 0, -1, -1, -1, 0, 1};

// 遞迴版
void nextPos(int x, int y) {
    passed[x][y] = true;
    for (int i = 0; i < 8; i++) {
        int nx = x + dx[i];
        int ny = y + dy[i];
        
        if (nx >= 0 && nx < row && ny >= 0 && ny < col && mp[nx][ny] == '@' && !passed[nx][ny]) {
            nextPos(nx, ny);
        }
    }
}

// dfs版，用stack實作
void dfs(int i, int j){
    passed[i][j] = true;
    stack<pair<int, int>> st;
    st.push({i, j});
    while(!st.empty()){
        pair<int, int> curr = st.top();
        st.pop();

        for(int i=0; i<8; ++i){
            int nx = curr.first + dx[i];
            int ny = curr.second + dy[i];

            if(nx < row && nx >= 0 && ny < col && ny >= 0 && mp[nx][ny] == '@' && !passed[nx][ny]){
                passed[nx][ny] = true;
                st.push({nx, ny});
            }
        }
    }
}

// bfs版，用queue實作
void bfs(int i, int j){
    passed[i][j] = true;
    queue<pair<int, int>> q;
    q.push({i, j});

    while(!q.empty()){
        pair<int, int> curr = q.front();
        q.pop();

        for(int i=0; i<8; ++i){
            int nx = curr.first + dx[i];
            int ny = curr.second + dy[i];

            if(nx < row && nx >= 0 && ny < col && ny >= 0 && mp[nx][ny] == '@' && !passed[nx][ny]){
                passed[nx][ny] = true;
                q.push({nx, ny});
            }
        }
    }
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    while(cin >> row >> col && row != 0){
        for(int i=0; i<row; ++i){
            for(int j=0; j<col; ++j){
                cin >> mp[i][j];
                passed[i][j] = false;
            }
        }
        int oilCounts = 0;

        for(int i=0; i<row; ++i){
            for(int j=0; j<col; ++j){
                if(mp[i][j] == '@' && !passed[i][j]){
                    ++oilCounts;
                    // nextPos(i, j);
                    // dfs(i, j);
                    bfs(i, j);
                }
                passed[i][j] = true;
            }
        }

        cout << oilCounts << '\n';
    }
    return 0;
}