An array lookup of "algorithm" spanning search

Topic 1: give a one-dimensional array A, size n, the absolute value of the difference between adjacent elements is 1. such as a = [1, 0, 1, 2, 3, 2, 1, 2, 3], now given a and target find Num. Please find the position of NUM in the array.
Topic 2: on the premise of topic one, now returns all index positions of Num.

idea: traversal can be implemented sequentially, but the complexity O (N).
If the first element of the array is a[0], the number to find is Num. Set T = ABS (Num-a[0]). Since the absolute value of each adjacent number is 1, the number before the T-position is definitely smaller than Num. So the next search is anchored to a[t]. Recalculate T, T = ABS (Num-a[t]), repeat the above steps. The difference between the current position and the lookup number is used to achieve a leap-forward search. This search method is a bit higher than traversing an array.
Topic one and topic two is actually a problem, the topic after finding the element is returned, the topic two to search until the end of the array.

AC Code:

#include <iostream>#include <stdio.h>#include <math.h>#include <vector>using namespace STD;intFindnuminarray (intArr[],intNintNUM) {intNextindex =ABS(num-arr[0]); while(Nextindex < N) {if(Arr[nextindex] = = num)returnNextindex; Nextindex + =ABS(Num-arr[nextindex]); }return-1;}voidFindallnuminarray (intArr[],intNintNum vector<int>& ret) {intNextindex =ABS(num-arr[0]); while(Nextindex < N) {if(Arr[nextindex] = = num)            {Ret.push_back (Nextindex);        ++nextindex; }Else{Nextindex + =ABS(Num-arr[nextindex]); }    }return;}voidMain () {Const intMaxLen =Ten;intArr[maxlen] = {1,0,1,2,3,2,1,2,3,4};//Test topic One, find the index of the first matching number    printf("Find%d, \ t subscript%d, \ t is actually subscript 0\n",1, Findnuminarray (arr, MaxLen,1));printf("Find%d, \ t subscript%d, \ t is actually subscript 4\n",3, Findnuminarray (arr, MaxLen,3));printf("Find%d, \ t subscript%d, \ t is actually subscript 9\n",4, Findnuminarray (arr, MaxLen,4));printf("Find%d, \ t subscript%d, \ t is actually subscript -1\n",-1, Findnuminarray (arr, MaxLen,-1));//Test topic Two, return all indexes     vector<int>Ret Findallnuminarray (arr, MaxLen,1, ret);if(!ret.empty ()) { for( vector<int>:: Size_type i =0; I < ret.size (); i++)printf("Look for index%d \ t subscript%d",1, Ret[i]); } getchar ();return;}

Operation Result:

An array lookup of "algorithm" spanning search