C++ 中检查矩阵是否为上三角形的程序
给定一个方阵 M[r][c],其中“r”是行数,“c”是列数,且 r = c,我们要检查“M”是否是上三角形矩阵。
上三角形矩阵
上三角形矩阵是指主对角线(包括主对角线)以上元素不为零,以下元素都为零的矩阵。
例如以下示例 −
在上图中,以红色高亮的元素是主对角线以下的元素,都为零,而其余元素都非零。
示例
Input: m[3][3] = { {1, 2, 3}, {0, 5, 6}, {0, 0, 9}} Output: yes Input: m[3][3] == { {3, 0, 1}, {6, 2, 0}, {7, 5, 3} } Output: no
算法
Start Step 1 -> define macro as #define size 4 Step 2 -> Declare function to check matrix is lower triangular matrix bool check(int arr[size][size]) Loop For int i = 1 and i < size and i++ Loop For int j = 0 and j < i and j++ IF (arr[i][j] != 0) return false End End End Return true Step 3 -> In main() Declare int arr[size][size] = { { 1, 1, 3, 2 }, { 0, 3, 3, 2 }, { 0, 0, 2, 1 }, { 0, 0, 0, 1 } } IF (check(arr)) Print its a lower triangular matrix End Else Print its not a lower triangular matrix End Stop
示例
#include <bits/stdc++.h> #define size 4 using namespace std; // check matrix is lower triangular matrix bool check(int arr[size][size]){ for (int i = 1; i < size; i++) for (int j = 0; j < i; j++) if (arr[i][j] != 0) return false; return true; } int main(){ int arr[size][size] = { { 1, 1, 3, 2 }, { 0, 3, 3, 2 }, { 0, 0, 2, 1 }, { 0, 0, 0, 1 } }; if (check(arr)) cout << "its a lower triangular matrix"; else cout << "its not a lower triangular matrix"; return 0; }
输出
its a lower triangular matrix
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