Java interview-Classic algorithm questions

Topic One:

public class Testclockwiseoutput {//print a matrix clockwise  @Test public void Test () {int[][] num = new INT[100][100]; int n = 4; i NT count = 1; for (int i=0;i<n;i++) {for (int J =0;j<n;j++) {                num[i][j]=count++;            }        }                Output (num,0,n-1);    } public void output (int[][] num,int Start,int end) {if (Start>=end | | end<=0) return, for (int i=start;i<=end;i++) {            System.out.println (Num[start][i]);        } for (int i=start+1;i<=end;i++) {            System.out.println (Num[i][end]),        } for (int i=end-1;i>=start;i--) {            System.out.println (Num[end][i]);        } for (int i=end-1;i>start;i--) {            System.out.println (Num[i][start]);        }        Output (num,start+1,end-1);}    }

Topic Two:

A sorted array and a number are given, and the sum of successive elements in the array is equal to the given number of sub-arrays.

A sorted array and a number are given, and the sum of contiguous elements in the array is equal to the number of substrings  @Test public void Test () {int[] num = {1,2,2,3,4,5,6,7,8,9}; int sum = 7;        Findsum (num,sum);    } public void Findsum (int[] num,int sum) {int. left=0; int right=0; for (int i=0;i<num.length;i++) {int cursum = 0;            left = i;            right = i; while (cursum<sum) {                cursum + = num[right++];            } if (Cursum==sum) {for (int j=left;j<right;j++) {                    System.out.print (num[j]+ "");                }                System.out.println ();}}}    

Topic Three:

The character array consists of all the strings  @Test public void Test () {//char[] cs = {' A ', ' B ', ' C ', ' d ', ' e '};  Char[] cs = {' A ', ' B ', ' C '}; int length = Cs.length;                Recursionswap (cs,0,length);    } public void Swap (char[] cs,int index1,int index2) {Char temp = cs[index1];        CS[INDEX1]=CS[INDEX2];        cs[index2]=temp;            } public void Recursionswap (char[] cs,int start,int length) {if (start>=length-1) {            print (CS); return;        } for ( int i=start;i<length;i++) {            swap (cs,start,i);            Recursionswap (cs,start+1,length);                Swap (cs,start,i);        }    } public void print (char[] cs) {for (int i=0;i<cs.length;i++) {            System.out.print (cs[i]);        }        System.out.println ();    }

Topic Four:

The minimum number of array composition @Test public void Test () {int[] num={1,5,9,13,442,44,6,21,211};        Qsort (num,0,num.length-1);    SYSTEM.OUT.PRINTLN (arrays.tostring (num));            } public void Qsort (int[] Num,int left,int right) {if (left<right) {int partition = partition (Num,left,right);            Qsort (num,left,partition-1);        Qsort (Num,partition+1,right); }} public int partition (int[] Num,int left,int right) {int partition = Num[left], while (Left<right) {while (num [Right]==partition | |            Ismbigerthann (num,num[right],partition) && left<right) {right--; } swap (Num,left,right);            while ((Num[left]==partition | | Ismbigerthann (num,partition,num[left)) && left<right) {left++;                } swap (Num,left,right);    } return left;        } public void Swap (int[] num,int m,int n) {int temp = num[m];        Num[m]=num[n];    Num[n]=temp; } public boolean Ismbigerthann (int[] Num,int m,int N) {String num1 = string.valueof (m); String num2 = string.valueof (n); int temp1 = Integer.parseint (num1+num2); int temp2 = Integer.parseint (NUM2+NUM1);        if (TEMP1&GT;TEMP2) {return true;        } else{return false; }    }

Topic Five:

Sub-array Max and  @Test public void Test () {int[] num = {1,-2,3,10,-4,7,2,-5};//int[] num = {1,-2,3,10,-4,10,2,-5};  SYSTEM.OUT.PRINTLN (Maxsum (num));    } public int maxsum (int[] num) {int cursum = 0, int curmaxsum = -99999999; int start = 0; int end = 0; for (int i=0;i<num. length;i++) {if (cursum<=0) {                cursum = num[i];                start = i;            } else{                cursum + = Num[i];            } if (cursum>curmaxsum) {                curmaxsum = cursum;                        end = i;            }        } for (int i = start;i<=end;i++) {            System.out.println (num[i]);        } return curmaxsum;    }

Topic Six:

 public class Testminstack {//custom stack, min function gets the current minimum @Test public void Test () {Minstack ms = new Minstack ();        Ms.push (5);        System.out.println (Ms.min ());        Ms.push (6);        Ms.push (2);        Ms.push (1);        System.out.println (Ms.min ());        Ms.pop ();        System.out.println (Ms.min ());        Ms.pop ();            System.out.println (Ms.min ());  }} class minstack{private stack<integer> Minstack = new stack<integer> (); private stack<integer> Stack = new Stack<integer> ();    public int pop () {minstack.pop (); return Stack.pop ();        public void push (int num) {if (Minstack.size () <=0) {minstack.push (num); return; } Integer min = Minstack.lastelement ();        if (num<min) {minstack.push (num);        } else{Minstack.push (min);    } stack.push (num);        } public int min () {if (Minstack.size () <=0) {return-1;    } return Minstack.lastelement (); }}

Topic Seven:

Find out how many occurrences in the array are greater than half  @Test public void Test () {int[] num = {1,2,2,2,2,2,2,4,2,4,6,4,2,6,8,2,7,7};        SYSTEM.OUT.PRINTLN (Morethanhaft (num));    } public int morethanhaft (int[] num) {int result =-1; int times = 0, for (int i=0;i<num.length;i++) {if (times==0) {                re Sult = Num[i];                times++;            } else{if (num[i]==result) {                    times++;                } else{                    times--;}}        } return result;    

Topic Eight:

Determines whether an array is the stacking order of another stack  @Test public void Test () {int[] num = {1,2,3,4,5};//int[] num1={1,2,3,5,4}; int[] num2={2,1,5,3 , 4};        stack<integer> S1 = new stack<integer> ();        stack<integer> s2 = new stack<integer> (); for (int i=0;i<5;i++) {            s2.push (num2[i]);        }                System.out.println (Testorder (NUM,S1,S2));    } public boolean Testorder (int[] num,stack<integer> s1,stack<integer> s2) {int length = num.length, for (int i=0 ; i<length;i++) {            s1.push (num[i]); int s2num = S2.lastelement (); if (S2num==s1.lastelement (). Intvalue ()) {                S1.pop ();                S2.pop ();            }        } while (!s1.isempty ()) {if (!s1.pop (). Equals (S2.pop ())) {return false;            }        } return true;    }

Topic Nine:

Draw 5 cards from poker, 0 can be any number, determine whether the CIS @Test public void Test () {int[] num = {0,1,5,3,2};    SYSTEM.OUT.PRINTLN (check (num));        } public boolean check (int[] num) {//0-13 int[] pai = new int[14], for (int n:num) {pai[n]+=1; } qsort (num,0,num.length-1); int count = pai[0]; int start = 0;        if (num[0]==0) {start=num[1];        } else{start=num[0];            } for (int i = start;i<=start+5;i++) {if (pai[i]>1) return false;        Count + = Pai[i]; } if (count = = 5) return true;            else return false;            } public void Qsort (int[] Num,int left,int right) {if (left<right) {int partition = partition (Num,left,right);            Qsort (num,left,partition-1);        Qsort (Num,partition+1,right); }} public int partition (int[] Num,int left,int right) {int partition = Num[left], while (Left<right) {while (left<            Right && num[right]>=partition) {right--; } swap (Num,left,right); while (lEft<right && num[left]<=partition) {left++;        } swap (Num,left,right);            } return left;        } public void Swap (int[] num,int m,int n) {int temp = num[m];        Num[m]=num[n];    Num[n]=temp; }

Topic Ten:

Output K-Ugly (factor only 2,3,5) @Test public  void Test () {        finduglynum (8),} public    void finduglynum (int index) {int[] num = new Int[index]; int next = 1;        Num[0]=1; int index2=0; int index3=0; int index5=0; while (next<index) {int num2 = num[index2]*2; int num3 = num[index3]*3; int num5 = num[index5]*5;                        Num[next] = getsuitable (NUM2,NUM3,NUM5); while (Num[index2]*2<=num[next]) {                index2++,            } while (Num[index3]*3<=num[next]) {                index3++;            } while (Num[index5]*5<=num[next]) {                index5++;            }                            next++;                    }        System.out.println (Num[index-1]);    } public int getsuitable (int num2,int num3,int NUM5) {int s = num2; if (num3<s) {            s = num3;        } if (num5<s) {
   
    s = NUM5;        } return s;    }
   

Java interview-Classic algorithm questions