二分查找算法

1、已经排序的数组，查找索引最小的值：

int binary_search(int[] array, int n, int value)
{
    int maxIndex = n;
    int minIndex = 1;
    int index;
    while (maxIndex >= minIndex)
    {
        index = (maxIndex + minIndex) / 2;
        if (array[index - 1] == value)
        {
            while (--index > 0)
            {
                if (array[index - 1] == value) continue;
                break;
            }
            return index;
        }
        if (array[index - 1] > value)
        {
            maxIndex = index - 1;
            continue;
        }
        if (array[index - 1] < value)
        {
            minIndex = index + 1;
            continue;
        }
    }
    return -1;
}

　　调用方法：

int index = binary_search(new[] { 1 }, 1, 1);
index = binary_search(new[] { 1 }, 1, 2);
index = binary_search(new[] { 1, 2 }, 2, 2);
index = binary_search(new[] { 1, 2 }, 2, 1);
index = binary_search(new[] { 1, 2 }, 2, 3);
index = binary_search(new[] { 1, 2, 3 }, 3, 2);
index = binary_search(new[] { 1, 2, 3 }, 3, 3);
index = binary_search(new[] { 1, 2, 3 }, 3, 1);
index = binary_search(new[] { 1, 2, 3 }, 3, 4);
index = binary_search(new[] { 1, 2, 3, 3, 3, 3, 3, 4 }, 8, 3);
index = binary_search(new[] { 1, 2, 3, 4 }, 4, 4);
index = binary_search(new[] { 1, 2, 3, 4 }, 4, 2);
index = binary_search(new[] { 1, 2, 3, 4 }, 4, 1);
index = binary_search(new[] { 1, 2, 3, 4 }, 4, 5);