（1）线性查找和二分搜索

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线性查找算法遍历数组，直到找到查询内容，其时间复杂度为O(n)。

public static int lineatSearch(int[] list,int key)    {        for(int i=0;i<list.length;i++)        {            if(key==list[i])               return i;         }        return -1;    }

二分搜索算法的时间复杂度为O(logn).

public static int binarySearch(int[] list,int key)    {        int low=0;        int high=list.length-1;        while(high>=low){            int mid=(low+high)/2;            if(key<list[mid])                high=mid-1;            else if(key==list[mid])                return mid;            else low=mid+1;        }        return -low-1;    }/** Use binary search to find the key in the list */  public static<E extends Comparable<E>> int binarySearch(E[] list, E key) {    int low = 0;    int high = list.length - 1;    while (high >= low) {      int mid = (low + high) / 2;      if (key.compareTo(list[mid]) < 0) {        high = mid - 1;      }      else if (key.equals(list[mid])) {        return mid;      }      else {        low = mid + 1;      }    }    return -low - 1; // Now high < low  }

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