源代碼:
#include<stdio.h>
#include<stdlib.h>
#include<iostream>
#include<algorithm>
using namespace std;
//這個算法僅適用於有序序列
int a[1000];
int BinarySearch1(int a[], int left, int right, int x)
{
int mid;
mid = (left + right) / 2;
if(left < right) {
if (x == a[mid])
return mid;
else if (x < a[mid])
return BinarySearch1(a, left, mid - 1, x);//遞歸調用前一半數組
else
return BinarySearch1(a, mid + 1, right, x);//。。。後一半。。。
}
return 0;
}
int BinarySearch2(int a[], int left, int right, int x)
{
int mid;
while (left <= right) {
mid = (left + right) / 2;
if (x == a[mid])
return mid;
else if (x < a[mid])
right = mid - 1;//遞歸調用前一半數組
else
left = mid + 1;//。。。後一半。。。
}
return 0;
}
int main()
{
int x, n, flag = 0;
cin >> x >> n;
for (int i = 1; i <= n; i++)
cin >> a[i];
flag = BinarySearch2(a, 1, n, x);
if (flag)
printf("%d", flag);
else
printf("no answer");
return 0;
}
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