布尔矩阵问题 · GeeksForGeeks 中文系列教程

# 布尔矩阵问题 > 原文： [https://www.geeksforgeeks.org/a-boolean-matrix-question/](https://www.geeksforgeeks.org/a-boolean-matrix-question/) 给定大小为 MXN 的布尔矩阵 mat [M] [N]，请对其进行修改，以使如果矩阵单元 mat [i] [j]为 1（或 true），则使第 i 行和第 j 列的所有单元格均为 1。 ``` Example 1 The matrix 1 0 0 0 should be changed to following 1 1 1 0 Example 2 The matrix 0 0 0 0 0 1 should be changed to following 0 0 1 1 1 1 Example 3 The matrix 1 0 0 1 0 0 1 0 0 0 0 0 should be changed to following 1 1 1 1 1 1 1 1 1 0 1 1 ``` **方法 1（使用两个临时数组）** 1）创建两个临时数组 row [M]和 col [N]。将 row []和 col []的所有值初始化为 0。 2）遍历输入矩阵 mat [M] [N]。如果看到输入 mat [i] [j]为 true，则将 row [i]和 col [j]标记为 true。 3）再次遍历输入矩阵 mat [M] [N]。对于每个入口 mat [i] [j]，检查 row [i]和 col [j]的值。如果两个值（row [i]或 col [j]）中的任何一个为 true，则将 mat [i] [j]标记为 true。感谢 Dixit Sethi 提出了这种方法。 ## C++ ```cpp // C++ Code For A Boolean Matrix Question #include <bits/stdc++.h> using namespace std; #define R 3 #define C 4 void modifyMatrix(bool mat[R][C]) { bool row[R]; bool col[C]; int i, j; /* Initialize all values of row[] as 0 */ for (i = 0; i < R; i++) { row[i] = 0; } /* Initialize all values of col[] as 0 */ for (i = 0; i < C; i++) { col[i] = 0; } // Store the rows and columns to be marked as // 1 in row[] and col[] arrays respectively for (i = 0; i < R; i++) { for (j = 0; j < C; j++) { if (mat[i][j] == 1) { row[i] = 1; col[j] = 1; } } } // Modify the input matrix mat[] using the // above constructed row[] and col[] arrays for (i = 0; i < R; i++) { for (j = 0; j < C; j++) { if ( row[i] == 1 || col[j] == 1 ) { mat[i][j] = 1; } } } } /* A utility function to print a 2D matrix */ void printMatrix(bool mat[R][C]) { int i, j; for (i = 0; i < R; i++) { for (j = 0; j < C; j++) { cout << mat[i][j]; } cout << endl; } } // Driver Code int main() { bool mat[R][C] = { {1, 0, 0, 1}, {0, 0, 1, 0}, {0, 0, 0, 0}}; cout << "Input Matrix \n"; printMatrix(mat); modifyMatrix(mat); printf("Matrix after modification \n"); printMatrix(mat); return 0; } // This code is contributed // by Akanksha Rai(Abby_akku) ```