[Programming Pearl] Chapter 4: Compile the correct program

1. subscripts: 0 <= l u <= n-1

2. This function can be written as follows:

 
# Include <iostream> using namespace STD; int BS (int * a, int begin, int end, int v) {int * B = a + begin; // start int * E = a + end; // end int * mid = NULL; // The while (B <E) // until it is equal to the first value that appears {mid = B + (e-B)> 1); // obtain the address in the center if (* mid> = V) E = mid; else B = Mid + 1;} If (e-a) <End & (* E = V) Return e-; return-1;} int main () {int A [5] = {1, 2, 2, 4}; cout <BS (A, 0, 4, 2) <Endl; return 0 ;}
 

Test againCode

# Include <stdio. h> # include <stdlib. h> int CMP (const void * a, const void * B) {return (* (int *) A)-(* (int *) B );} int BS (int * a, int begin, int end, int v) {int * B = a + begin, * E = a + end, * mid = NULL; If (! A) return NULL; while (B <E) {mid = B + (e-B)> 1); If (* mid> = V) E = mid; else if (* mid <v) B = Mid + 1;} If (e-a) <End & (* E = V) Return e-; return-1;} int find (int * a, int begin, int end, int v) {int I = 0; for (I = begin; I <end; ++ I) if (a [I] = V) return I; Return-1 ;}int main (void) {int A [10000]; int n = 10000, I = 0; int F, E; for (I = 0; I <n; ++ I) A [I] = random () % 100; Qsort (A, N, sizeof (INT), CMP); for (I = 0; I <n; ++ I) {f = find (A, 0, n, A [I]); E = BS (A, 0, n, a [I]); If (F! = E) printf ("error find of % d \ n", a [I], F, E) ;}return 0 ;}

6,ProgramEnd-to-End proof: each step will throw at least one bean, so it will always end. In addition, the white beans are either two or not thrown. If the white beans are odd, the white beans are left with a white bean; otherwise, the white beans are black beans.

7. If you want to use binary search in the question, you need to find a lower limit of the number.

Using the method in question 2, you can find the upper bound. Because the line segments are arranged sequentially, you can find the lower bound.