2分查找法 binsearch

2分查找法，嘿嘿

/* binsearch: find x in v[0] <= v[1] <= ... <= v[n-1] */
   int binsearch(int x, int v[], int n)
   {
       int low, high, mid;

       low = 0;
       high = n - 1;
       while (low <= high) {
           mid = (low+high)/2;
           if (x < v[mid])
               high = mid + 1;
           else if (x > v[mid])
               low = mid + 1;
           else /* found match */
               return mid;
       }
       return -1; /* no match */
   }


这个用了2个test，下面使用一个test

/* binsearch: find x in v[0] <= v[1] <= ... <= v[n-1] ; 2ed version */
   int binsearch(int x, int v[], int n)
   {
       int low, high, mid;

       low = 0;
       high = n - 1;
       while (low <= high) {
           mid = (low+high)/2;
           if ( x != v[mid]
        (x < v[mid]) ? (high = mid + 1) : (low = mid + 1);
           else /* found match */
               return mid;
       }
       return -1; /* no match */
   }