Sort colors

Signed-off-by: Leo Ma <[email protected]>

075_sort_colors/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test sort_colors.c

075_sort_colors/sort_colors.c

@@ -0,0 +1,57 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void swap(int *a, int *b)
+{
+    int tmp = *a;
+    *a = *b;
+    *b = tmp;
+}
+
+/*
+ * RED = 0
+ * WHITE = 1
+ * BLUE = 2
+ */
+static void sortColors(int* nums, int numsSize) {
+    int i = 0, j = numsSize - 1;
+    while (i < j) {
+        while (nums[i] == 0 && i < j) {
+            i++;
+        }
+        while (nums[j] != 0 && j > i) {
+            j--;
+        }
+        swap(nums + i, nums + j);
+    }
+    j = numsSize - 1;
+    while (i < j) {
+        while (nums[i] == 1 && i < j) {
+            i++;
+        }
+        while (nums[j] != 1 && j > i) {
+            j--;
+        }
+        swap(nums + i, nums + j);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "Usage: ./test colors\n");
+        exit(-1);
+    }
+    int i, count = strlen(argv[1]);
+    int *nums = malloc(count * sizeof(int));
+    for (i = 0; i < count; i++) {
+        nums[i] = argv[1][i] - '0';
+    }
+    sortColors(nums, count);
+    for (i = 0; i < count; i++) {
+        printf("%d", nums[i]);
+    }
+    printf("\n");
+    return 0;
+}