Data structure and algorithm (i.)

1. What is an algorithm

Your own understanding is the way to solve the problem.

The essence of work is to solve the problem--Peter Drucker

2. Cycle

Loop four elements: Initialize variables, loop conditions, change iterations of loop variables, loop code blocks

While: first judge the cycle conditions, after the execution of the loop body;

Do While: first the loop body is executed, then the cyclic condition is judged;

The difference between the two: under normal operating conditions, while will be more than do while more judgment, the output is consistent;

In the case of abnormal operation, the loop body in while is not executed, and the Do while runs the loop body;

 Public classalgorithm{ Public Static voidMain (string[] args) {intA = 1;  while(a<5) {System.out.println (a); A++; }                intb = 1;  Do{System.out.println (b); b++; } while(b<5); }    }

View Code

Find out all narcissus numbers:

 Public classalgorithm{//number of daffodils: a three-digit number 1000 cubic and equal to the number itself; Select all narcissus numbers     Public Static voidMain (string[] args) {intA = 100;  while(a<1000){                        intb = a/100; intc = a/10%10; intD = a%10; if(A = = B*b*b + c*c*c +d*d*d)                            {System.out.println (a); } A= A+1; }            }    }

View Code

 Public classalgorithm{//number of daffodils: a three-digit number 1000 cubic and equal to the number itself; Select all narcissus numbers     Public Static voidMain (string[] args) { for(intA = 100; a<1000; a++){                        intb = a/100; intc = a/10%10; intD = a%10; if(A = = b*b*b+c*c*c+d*d*d)            {System.out.println (a); }                    }            }    }

View Code

Iterate through the array to find the maximum/minimum value

 Public classalgorithm{//traverse Array a[] to find the maximum value     Public Static voidMain (string[] args) {intA[] = {-}; intx = a[0];  for(inti=0; i<a.length; i++){                    if(a[i]>x) {x=A[i];        }} System.out.println (x); }    }

View Code

Bubble sort

 Public classalgorithm{//iterate over array a[], sorted by large to small     Public Static voidMain (string[] args) {intA[] = {1,3,2,8,7};  for(inti=0;i<a.length-1;i++){         for(intj=0;j<a.length-1-i;j++){                        if(a[j]<a[j+1]){                intx=A[j]; A[J]=a[j+1]; A[j+1] =x; }                    }            }     for(inti=0;i<a.length;i++) {System.out.println (a[i]); }    }    }

View Code

Data structure and algorithm (i.)