Leetcode27--->remove element (to Remove the given element in the divisor Group)

title: Given an array of arrays and a value, remove all elements equal to the value in the array, return the length of the new array, request: cannot allocate extra array space, and must use the idea of in-place ordering, spatial complexity o (1);

Example:

Given input array nums = [3,2,2,3] , val =3

Your function should return length = 2, with the first of the elements of nums being 2.

Problem solving Ideas:

1. First find the first position equal to value and the first number not equal to value;

2. The number equal to value and not equal to value is all value;

3. Each exchange must be the first equal to value and the first number that is not equal to value for exchange;

To Illustrate:

3,3,3,2,2,3,1,2,4,3,4,3,2; Value = 3

1) initial: start = 0; index = 3; The number of exchange two locations, the result becomes: 2,3,3,3,2,3,1,2,4,3,4,3,2;

2) start = 1; index = 4; exchange:2,2, 3,3,3,3,1,2,4,3,4,3,2;

3) start = 2; index = 5; because nums[index] = 3, so index is incremented until nums[index]! = 3, at which point index = 6; exchange:2,2, 1,3,3,3,3,2,4,3,4,3,2;

4) start = 3; index = 7;exchange:2,2, 1,2,3,3,3,3,4,3,4,3,2;

5) start = 4; index = 8; exchange:2,2, 1,2,4,3,3,3,3,3,4,3,2;

6) start = 5; index = 9; nums[index] = 3, index is incremented until index = 10:exchange:2,2, 1,2,4,4,3,3,3,3,3,3,2;

7) start = 6; index = 11; nums[index] = 3, index is incremented until index = 12:exchange:2,2, 1,2,4,4,2,3,3,3,3,3,3;

At this point start = 7;index = 12 equals the length of the array, ending;

The code is as Follows:

1  public classSolution {2      public intRemoveelement (int[] nums,intVal) {3         if(nums = =NULL|| Nums.length < 1){4                 return0;5         }6         intCount = 0;7         intindex = 0;8          while(index < nums.length && nums[index]! = Val) {index + +; count + +;}//find the first number equal to value9         intStart =index;Ten          while(index < nums.length && nums[index] = = Val) {index + +;}//find the first number that is not equal to value one          while(start < nums.length && Index <Nums.length) { a Exchange (nums, start, index); -Count + +; -Start + +; the              while(index < nums.length && nums[index] = = Val) {index + +;} -  -         } -         returncount; +     } -       public Static voidExchangeint[] nums,intindex1,intindex2) +      { a         inttemp =nums[index1]; atnums[index1] =nums[index2]; -nums[index2] =temp; -      } -}

Leetcode27--->remove element (to Remove the given element in the divisor Group)