From a0b7f8badde02e398f45dbef848d3ddeef1da5ee Mon Sep 17 00:00:00 2001
From: pjc97uv2f <1291955673@qq.com>
Date: Fri, 29 Nov 2024 15:11:14 +0800
Subject: [PATCH] Add 3

---
 3 | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 3

diff --git a/3 b/3
new file mode 100644
index 0000000..53c435b
--- /dev/null
+++ b/3
@@ -0,0 +1,72 @@
+#include <iostream>
+#include <ctime>  // 用于 clock() 函数
+#include <cstdlib>  // 用于 rand() 函数
+#include <cstdio>   // 用于 printf 函数
+
+// 定义矩阵大小
+#define SIZE 1024
+
+// 矩阵乘法函数
+void matmul(float** A, float** B, float** C, int n) {
+    // 初始化结果矩阵 C 为 0
+    for (int i = 0; i < n; ++i) {
+        for (int j = 0; j < n; ++j) {
+            C[i][j] = 0;
+        }
+    }
+
+    // 矩阵乘法，C[i][j] = A[i][k] * B[k][j] 的累加
+    for (int i = 0; i < n; ++i) {
+        for (int j = 0; j < n; ++j) {
+            for (int k = 0; k < n; ++k) {
+                C[i][j] += A[i][k] * B[k][j];
+            }
+        }
+    }
+}
+
+int main() {
+    // 动态分配矩阵内存
+    float** A = new float*[SIZE];
+    float** B = new float*[SIZE];
+    float** C = new float*[SIZE];
+    for (int i = 0; i < SIZE; ++i) {
+        A[i] = new float[SIZE];
+        B[i] = new float[SIZE];
+        C[i] = new float[SIZE];
+    }
+
+    // 初始化 A 和 B 矩阵的元素为随机值
+    srand(static_cast<unsigned>(time(0)));  // 使用时间作为随机种子
+    for (int i = 0; i < SIZE; ++i) {
+        for (int j = 0; j < SIZE; ++j) {
+            A[i][j] = rand() % 100;  // 随机数0到99
+            B[i][j] = rand() % 100;  // 随机数0到99
+        }
+    }
+
+    // 计时开始
+    clock_t start = clock();
+
+    // 执行矩阵乘法
+    matmul(A, B, C, SIZE);
+
+    // 计时结束
+    clock_t end = clock();
+
+    // 计算并输出运行时间
+    double elapsed_time = double(end - start) / CLOCKS_PER_SEC;
+    printf("矩阵乘法执行时间: %.6f 秒\n", elapsed_time);
+
+    // 释放动态分配的内存
+    for (int i = 0; i < SIZE; ++i) {
+        delete[] A[i];
+        delete[] B[i];
+        delete[] C[i];
+    }
+    delete[] A;
+    delete[] B;
+    delete[] C;
+
+    return 0;
+}
\ No newline at end of file