Search in rotated sorted array

Signed-off-by: begeekmyfriend <[email protected]>

033_search_in_rotated_sorted_array/Makefile

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

033_search_in_rotated_sorted_array/rotated_array.c

@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+static int binary_search(int *nums, int size, int target)
+{
+    int low = -1;
+    int high = size;
+    while (low + 1 < high) {
+        int mid = low + (high - low) / 2;
+        if (target > nums[mid]) {
+            low = mid;
+        } else {
+            high = mid;
+        }
+    }
+    if (high == size || nums[high] != target) {
+        return -1;
+    } else {
+        return high;
+    }
+}
+
+static int start_find(int *nums, int size)
+{
+    int low = 0;
+    int high = size - 1;
+    while (low < high && nums[low] > nums[high]) {
+        int mid = low + (high - low) / 2;
+        if (nums[mid] > nums[high]) {
+            low = mid + 1;
+        } else if (nums[mid] < nums[low]) {
+            /* Assume no duplicate exists in arry */
+            high = mid;
+        }
+    }
+    return low;
+}
+
+static int search(int* nums, int numsSize, int target) {
+    if (numsSize <= 0) {
+        return -1;
+    }
+    if (numsSize == 1) {
+        return target == nums[0] ? 0 : -1;
+    }
+
+    int i = start_find(nums, numsSize);
+    if (i == 0) {
+        return binary_search(nums, numsSize, target);
+    } else if (target >= nums[0]) {
+        return binary_search(nums, i, target);
+    } else if (target <= nums[numsSize - 1]) {
+        int index = binary_search(nums + i, numsSize - i, target);
+        return index >= 0 ? index + i : -1;
+    } else {
+        return -1;
+    }
+}
+
+int main(int argc, char **argv)
+{
+    int i;
+    int target = atoi(argv[1]);
+    int size = argc - 2;
+    int *nums = malloc(size * sizeof(int));
+
+    for (i = 0; i < argc - 2; i++) {
+        nums[i] = atoi(argv[i + 2]);
+    }
+    printf("%d\n", search(nums, size, target));
+    return 0;
+}