leetcode 33. 搜索旋转排序数组

最新推荐文章于 2025-10-10 14:45:39 发布

原创最新推荐文章于 2025-10-10 14:45:39 发布 · 121 阅读

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本文深入探讨了在旋转数组中查找目标元素的算法实现。首先，通过一个静态函数定位旋转点，接着在有序部分进行二分查找。文章详细介绍了算法步骤，并提供了完整的代码示例，包括处理边界情况的方法。

static int search_start(int* nums, int numsSize, int start, int end)
{
    if (nums[start] < nums[end]) {
        return 0;
    }
    while (start <= end) {
        int tmp = (start + end) / 2;
        if (nums[tmp] > nums[tmp + 1]) {
            return tmp + 1;
        } else {
            if(nums[tmp] < nums[start]) {
                end = tmp - 1;
            } else {
                start = tmp + 1;
            }
        }
        //printf("start:%d end:%d size:%d\n", start, end, numsSize);
    }
    return start;
}
static int search_target(int* nums, int size, int target) {
    if (target > nums[size - 1] || target < nums[0]) {
        return -1;
    }
    int start = 0;
    int end = size - 1;
    while (start <= end) {
        int tmp = (start + end) / 2;
        if (nums[tmp] == target) {
            return tmp;
        } else {
            if (target < nums[tmp]) {
                end = tmp -1;
            } else {
                start = tmp + 1;
            }
        }
    }
    return -1;
}
int search(int* nums, int numsSize, int target)
{
    if(!nums || numsSize < 1) {
        return -1;
    }
    if (numsSize == 1) {
        return nums[0] == target ? 0 : -1;
    }

    if (nums[0] < nums[numsSize - 1]) {
        return search_target(nums, numsSize, target);
    }
    int start_pos = search_start(nums, numsSize, 0, numsSize - 1);
    int ret = 0;
    printf("start position:%d\n", start_pos);
    if (nums[start_pos] == target) {
        return start_pos;
    } else if (nums[0] <= target && nums[start_pos - 1] >= target) {
        ret = search_target(nums, start_pos, target);
        printf("line:%d target position:%d\n", __LINE__, ret);
        return ret;
    } else {
        ret = search_target(&nums[start_pos], numsSize - start_pos, target);
        printf("line:%d target position:%d\n", __LINE__, ret);
        return ret == -1 ? -1 : ret + start_pos;
    }

}