Data structure and algorithm (i.)

11 Logical Structure:

A: The collection structure data elements have no other relationship than they belong to a collection

B: A one-to-one relationship between linear structure data elements

C: There is a one-to-many hierarchical relationship between tree-structured data elements

D: A Many-to-many relationship between graphical structure data elements

2 Physical Structure

A: Sequential storage structure is the data structure stored in the address continuous storage unit, the logical relationship between the database and the physical relationship is consistent

B: Chain storage structure is to store data structure in any storage unit, this group of storage units can be continuous, or can be discontinuous

Two algorithm large o derivation

1: With constant 1 represents all addition constants (execution time constant)

2: In the modified run Count function, only the highest stratum is retained

3: If the highest stratum is present and not 1, the constant multiplied by the item is removed

　　

A constant order

int n=100,sum=0; A

sum = (1+n) *N/2; A

Time complexity O (1)

b Linear Order

for (i=0;i<n;i++) {/* Executes a statement with a time complexity of O (1) */}//n times

Time complexity O (n)

C Logarithmic order

int count=1;

while (count<n) {count = count*2}

Time complexity O (LOGN)

D Square Order

for (i=0;i<n;i++) {//n times

　　　　　　

for (j=0;j<n;j++) {//n times

}

}

Time complexity O (n^2)

Common time complexity O (1) < O (Logn) < O (n) < O (Nlogn) < O (n^2) < O (n^3) < O (2^n) < O (n!) < O (n^n)

　　

Data structure and algorithm (i.)