openacc optimize弗洛伊德算法代码
时间: 2023-07-05 15:11:38 浏览: 52
以下是使用 OpenACC 优化的 Floyd 算法代码示例:
```c
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <openacc.h>
#define INF 99999
void floyd(int **graph, int n) {
int i, j, k;
#pragma acc data copy(graph[0:n][0:n])
for (k = 0; k < n; k++) {
#pragma acc parallel loop collapse(2)
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
if (graph[i][k] + graph[k][j] < graph[i][j]) {
graph[i][j] = graph[i][k] + graph[k][j];
}
}
}
}
}
int main() {
int n, i, j;
printf("Enter number of vertices: ");
scanf("%d", &n);
int **graph = (int **) malloc(n * sizeof(int *));
for (i = 0; i < n; i++) {
graph[i] = (int *) malloc(n * sizeof(int));
}
srand(time(NULL));
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
if (i == j) {
graph[i][j] = 0;
} else if (rand() % 3 == 0) {
graph[i][j] = INF;
} else {
graph[i][j] = rand() % 20 + 1;
}
}
}
printf("Original graph:\n");
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
if (graph[i][j] == INF) {
printf("%7s", "INF");
} else {
printf("%7d", graph[i][j]);
}
}
printf("\n");
}
floyd(graph, n);
printf("\nNew graph:\n");
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
if (graph[i][j] == INF) {
printf("%7s", "INF");
} else {
printf("%7d", graph[i][j]);
}
}
printf("\n");
}
for (i = 0; i < n; i++) {
free(graph[i]);
}
free(graph);
return 0;
}
```
在上面的代码中,我们使用 `#pragma acc parallel loop` 和 `#pragma acc data` 指令来并行化 Floyd 算法的计算。`#pragma acc data` 指令用于将 `graph` 数组从主机内存复制到设备内存中,`#pragma acc parallel loop` 指令用于并行化 `i` 和 `j` 循环。为了避免访问冲突,我们还可以使用 `collapse(2)` 选项将 `i` 和 `j` 循环合并为一个循环。