sort using both lazy sort and shell-sort

(cherry picked from commit 0cbea99c3e77736b571ef7702a7f6a3ce6a031be)

project_euler/Problem 22/sol1.c

@@ -0,0 +1,138 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#ifdef _OPENMP
+#include <omp.h>
+#endif
+
+#define MAX_NAMES 6000  /* Maximum number of names to store */
+#define MAX_NAME_LEN 20 /* Maximum length of each name */
+
+/**
+ * Alphabetical sorting using 'shell sort' algorithm
+ **/
+void shell_sort(char data[][MAX_NAME_LEN], int LEN)
+{
+    const int gaps[] = {701, 301, 132, 57, 23, 10, 4, 1};
+    const int gap_len = 8;
+    int i, j, g;
+
+    for (g = 0; g < gap_len; g++)
+    {
+        int gap = gaps[g];
+        for (i = gap; i < LEN; i++)
+        {
+            char tmp_buffer[MAX_NAME_LEN];
+            strcpy(tmp_buffer, data[i]);
+
+            for (j = i; j >= gap && strcmp(data[j - gap], tmp_buffer) > 0; j -= gap)
+                strcpy(data[j], data[j - gap]);
+            strcpy(data[j], tmp_buffer);
+        }
+    }
+#ifdef DEBUG
+    for (i = 0; i < LEN; i++)
+        printf("%s\t", data[i]);
+#endif
+}
+
+/**
+ * Alphabetical sorting using 'lazy sort' algorithm
+ **/
+void lazy_sort(char data[][MAX_NAME_LEN], int LEN)
+{
+    int i, j;
+    for (i = 0; i < LEN; i++)
+    {
+        for (j = i + 1; j < LEN; j++)
+        {
+            if (strcmp(data[i], data[j]) > 0)
+            {
+                char tmp_buffer[MAX_NAME_LEN];
+                strcpy(tmp_buffer, data[i]);
+                strcpy(data[i], data[j]);
+                strcpy(data[j], tmp_buffer);
+            }
+        }
+    }
+#ifdef DEBUG
+    for (i = 0; i < LEN; i++)
+        printf("%s\t", data[i]);
+#endif
+}
+
+int main(int argc, char **argv)
+{
+    unsigned long COUNT = 0;
+    char *fname = "names.txt";
+    char names[MAX_NAMES][MAX_NAME_LEN];
+    short method = 0; /* sorting algorithm to use. 0 = lazy, 1 = shell-sort */
+
+    if (argc == 2)
+        method = atoi(argv[1]);
+
+    FILE *fp = fopen(fname, "rt");
+    if (!fp)
+    {
+        perror("Unable to open file");
+        return -1;
+    }
+
+    /**
+     * Loops to get total number of rows and columns in the file
+     **/
+    do
+    {
+        int ret = fscanf(fp, "\"%[^\",]\",", names[COUNT++]);
+        if (ret <= 0)
+            continue;
+        // printf("%s\t", names[COUNT - 1]);
+    } while (!feof(fp));
+    fclose(fp);
+
+    printf("\nTotal number of names: %lu\n", COUNT);
+
+    if (method == 0)
+    {
+        clock_t start_time = clock();
+        shell_sort(names, COUNT);
+        clock_t end_time = clock();
+        printf("\nShell sort: %.4g millisecond\n", 1e3 * (end_time - start_time) / CLOCKS_PER_SEC);
+    }
+    else if (method == 1)
+    {
+        clock_t start_time = clock();
+        lazy_sort(names, COUNT);
+        clock_t end_time = clock();
+        printf("\nLazy sort: %.4g millisecond\n", 1e3 * (end_time - start_time) / CLOCKS_PER_SEC);
+    }
+
+    long sum_score = 0;
+    clock_t start_time = clock();
+#ifdef _OPENMP
+#pragma omp parallel for schedule(runtime) reduction(+ \
+                                                     : sum_score)
+#endif
+#ifdef DEBUG
+    for (unsigned int i = 935; i < 940; i++)
+#else
+    for (unsigned int i = 0; i < COUNT; i++)
+#endif
+    {
+        unsigned int score = 0;
+        /* score the alphabets in i^th name */
+        for (int j = 0; names[i][j] != '\0'; j++)
+            score += names[i][j] - 'A' + 1; /* convert ASCII character to integer score */
+        sum_score += score * (i + 1);
+#ifdef DEBUG
+        printf("Name: %s\tScore: %u x %u = %lu\n", names[i], score, i + 1, (unsigned long)score * (i + 1));
+#endif
+    }
+    clock_t end_time = clock();
+    printf("Scoring time: %.4g millisecond\n", 1e3 * (end_time - start_time) / CLOCKS_PER_SEC);
+
+    printf("Total Score = %lu\n", sum_score);
+
+    return 0;
+}