UVa 806 四分树

题意：

分析：

类似UVa 297， 模拟四分树四分的过程， 就是记录一个左上角， 记录宽度wideth， 然后每次w/2这样递归下去。 注意全黑是输出0， 不是输出1234。

#include <bits/stdc++.h>
using namespace std;
// 1 2
// 3 4
const int base5[8] = {1,5,25,125,625,3125,15625,78125};
int n;
string G[70];
vector<int> code;
int dfs(int r, int c, int w,int num,int dep){
    int lt[5][2] = {{},{r,c},{r,c+w/2},{r+w/2,c},{r+w/2, c+w/2}};

    for(int i = 1; i <= 4; i++){
        int all_black = 1, have_black = 0;

        for(int j = lt[i][0]; j < lt[i][0] + w/2; j++){
            for(int k = lt[i][1]; k < lt[i][1] + w/2; k++){
                if(G[j][k] == '0'){
                    all_black = 0;
                }
                else {
                    have_black = 1;
                }
            }
        }
        if(all_black == 0){

            if(w == 2){//宽度为2四分，只有一个格子， 只能为白
                continue;
            }
            if(have_black)
                dfs(lt[i][0], lt[i][1], w/2, num + base5[dep]*i, dep + 1 );
        }
        else{
            code.push_back(num + base5[dep] * i);
        }
    }
}
void print(int r, int c, int w, int dep,int decode, int dec){
    int lt[5][2] = {{},{r,c},{r,c+w/2},{r+w/2,c},{r+w/2, c+w/2}};
    if(decode == 0){
        for(int i = r; i < r + w; i++){
            for(int j = c; j < c + w; j++ ){
                G[i][j] = '1';
            }
        }
        return;
    }

    dec = decode % 5;
    decode /= 5;


    for(int i = 1; i <= 4; i++){
        if(dec == i){
            print(lt[i][0], lt[i][1], w/2 , dep + 1,decode, dec);
        }
        else continue;
    }
}
int main(){
    ios::sync_with_stdio(false);
    int kase = 1;
    while(cin >> n && n){

        if(kase > 1) cout <<'
';
        cout << "Image "<<kase ++ << '
';

        if(n > 0){
            int flag = 0;
            for(int i = 0; i < n; i++){
                cin >> G[i];
                for(int j = 0; j < G[i].size(); j++){
                    if(G[i][j] == '0') flag = 1;
                }
            }
            if(!flag){//特判全黑
                cout << "0
";
                cout << "Total number of black nodes = 1"<< "
";
                continue;

            }

            if(n == 1){//特判n = 1 全白。
                cout << "Total number of black nodes = 0" << "
";
                continue;
           }


            dfs(0,0,n,0,0);
            sort(code.begin(), code.end());
            for(int i = 0; i < code.size(); i++){
                cout << code[i];
                if((i + 1) % 12 == 0 || i == code.size() - 1)
                    cout <<'
';
                else cout << ' ';
            }

            cout << "Total number of black nodes = "<< code.size() << '
';
            code.clear();
        }

        else {
            n = -n;
            for(int i = 0; i < n; i++){
                G[i] = "";
                G[i]. resize(n +7);//string要更改size才能下标访问
            }
            int decode;
            while(cin >> decode && decode != -1){
                print(0,0,n,0,decode, 0);
            }
            for(int i = 0; i < n; i++){
                for(int j = 0; j < n; j++){
                    if(G[i][j] == '1'){
                        cout << '*';
                    }
                    else cout << '.';
                }
                cout << '
';
            }
        }
    }


    return 0;
}