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38.数字在排序数组中出现的次数

时间:2015-07-10 22:24:50      阅读:178      评论:0      收藏:0      [点我收藏+]

标签:数组

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半段查找。

int GetFirstK(int* data, int length, int k, int start, int end)
{
if (start > end)
return -1;
int middleIndex = (start + end) / 2;
int middleData = data[middleIndex];
if (middleData == k)
{
if ((middleIndex > 0 && data[middleIndex - 1] != k) || middleINdex == 0)
return middleIndex;
else
end = middleIndex - 1;
}
else if (middleData > k)
end = middleIndex - 1;
else
start = middleIndex + 1;
return GetFirstK(data, length, k, start, end);
}

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int GetLastK(int* data, int length, int k, int start, int end)
{
if (start > end)
return -1;
int middleIndex = (start + end) / 2;
int middleData = data[middleIndex];
if (middleData == k)
{
if ((middleIndex <length-1 && data[middleIndex +1] != k) || middleINdex == length-1)
return middleIndex;
else
start= middleIndex+1;
}
else if (middleData < k)
start = middleIndex +1;
else
end = middleIndex - 1;
return GetLastK(data, length, k, start, end);
}

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int GetNumberOfK(int* data, int length, int k)
{
int number = 0;
if (data != NULL&&length > 0)
{
int first = GetFirstK(data, length, k,0, length - 1);
int last = GetLastK(data, length, k, 0, length - 1);
if (first > -1 && last > -1)
number = last - first + 1;
}
return number;
}

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版权声明:本文为博主原创文章,未经博主允许不得转载。

38.数字在排序数组中出现的次数

标签:数组

原文地址:http://blog.csdn.net/wangfengfan1/article/details/46834211

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