SOJ 1041. Pushing Boxes

题目大意：一矩形区域中有若干个箱子，每次能从上下左右四个方向推箱子，被推的箱子往前移动，但是不能被挤爆。

解题思路：直接模拟。

代码如下：

#include <cstdio>
#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
const int maxd = 25;

bool matrix[maxd][maxd];    // matrix[i][j] == true 表示位置(i,j)有内容
int vertical[maxd];
int horizonal[maxd];


void init(const int &rows, const int &cols) {
    for (int r = 0; r <= rows; ++r)
        for (int c = 0; c <= cols; ++c)
            matrix[r][c] = false;
}

void fillRight(const int &r, const int &c) {
    if (matrix[r][c]) {
        fillRight(r, c + 1);
    } else {
        matrix[r][c] = true;
    }
}

void fillLeft(const int &r, const int &c) {
    if (matrix[r][c]) {
        fillLeft(r, c - 1);
    } else {
        matrix[r][c] = true;
    }
}

void fillDown(const int &r, const int &c) {
    if (matrix[r][c]) {
        fillDown(r + 1, c);
    } else {
        matrix[r][c] = true;
    }
}

void fillUp(const int &r, const int &c) {
    if (matrix[r][c]) {
        fillUp(r - 1, c);
    } else {
        matrix[r][c] = true;
    }
}

int main() {
    int t = 0;
    int rows, cols;
    string right("right");
    string left("left");
    string down("down");
    string up("up");
    string done("done");

    while (++t, scanf("%d%d", &rows, &cols), rows && cols) {
        init(rows, cols);
        int n;
        scanf("%d", &n);
        int row, col;
        for (int i = 0; i < n; ++i) {
            scanf("%d%d", &row, &col);
            matrix[row][col] = true;
        }

        string op;
        int opNum;
        while (cin >> op, op != done) {
            cin >> opNum;
            for (int i = 0; i < rows; ++i) horizonal[i] = 0;
            for (int i = 0; i < cols; ++i) vertical[i] = 0;
            for (int r = 0; r < rows; ++r) {
                for (int c = 0; c < cols; ++c) {
                    if (matrix[r][c]) {
                        ++horizonal[r];
                        ++vertical[c];
                    }
                }
            }
            int maxHorizonal = 0, maxVertical = 0;
            for (int i = 0; i < rows; ++i) maxHorizonal = max(maxHorizonal, horizonal[i]);
            for (int i = 0; i < cols; ++i) maxVertical = max(maxVertical, vertical[i]);

            if (op == left) {
                int bound = min(opNum, cols - maxHorizonal);
                int begin = cols - 1, end = begin - bound;
                int count = 0;
                for (int r = 0; r < rows; ++r) {
                    for (int c = begin; c > end; --c) {
                        if (matrix[r][c]) {
                            matrix[r][c] = false;
                            fillLeft(r, end - count);
                        }
                    }
                }
            } else if (op == right) {
                int bound = min(opNum, cols - maxHorizonal);
                int begin = 0, end = bound;    // 左闭右开
                int count = 0;
                for (int r = 0; r < rows; ++r) {
                    for (int c = begin; c < end; ++c) {
                        if (matrix[r][c]) {
                            matrix[r][c] = false;    // 撤销位置中的物质
                            fillRight(r, end + count);
                        }
                    }
                }
            } else if (op == up) {
                int bound = min(opNum, rows - maxVertical);
                int begin = rows - 1, end = begin - bound;
                int count = 0;
                for (int c = 0; c < cols; ++c) {
                    for (int r = begin; r > end; --r) {
                        if (matrix[r][c]) {
                            matrix[r][c] = false;
                            fillUp(end - count, c);
                        }
                    }
                }
            } else if (op == down) {
                int bound = min(opNum, rows - maxVertical);
                int begin = 0, end = bound;
                int count = 0;
                for (int c = 0; c < cols; ++c) {
                    for (int r = begin; r < end; ++r) {
                        if (matrix[r][c]) {
                            matrix[r][c] = false;
                            fillDown(end + count, c);
                        }
                    }
                }
            }

        }
        // 输出
        printf("Data set %d ends with boxes at locations", t);
        for (int r = 0; r < rows; ++r) {
            for (int c = 0; c < cols; ++c) {
                if (matrix[r][c]) {
                    printf(" (%d,%d)", r, c);
                }
            }
        }
        printf(".
");
    }
    return 0;
}