二分法查找

function binSearch(seqList, keyType)
{ //在有序表R[1..n]中进行二分查找，成功时返回结点的位置，失败时返回零
var low=0, high=seqList.length-1, mid=0; //置当前查找区间上、下界的初值
while(low<=high){ //当前查找区间R[low..high]非空
mid=parseInt((low+high)/2);
if(seqList[mid] == keyType)
return mid; //查找成功返回
if(seqList[mid] > keyType)
high = mid-1; //继续在R[low..mid-1]中查找
else
low = mid+1; //继续在R[mid+1..high]中查找
}
return -1; //当low>high时表示查找区间为空，查找失败
}