刷题笔记day3-day4

6-10 二分查找  

注意notfound的用法

Position BinarySearch( List L, ElementType x )
{
    int left = 1;
    int right = L->Last;

    while(left <= right)
    {
        int mid = (left + right )/2;
        if(L->Data[mid] == x) return mid;
        else if(L->Data[mid] > x)
        {
            right = mid-1;
        }
        else
        {
            left = mid + 1;
        }
    }
    return NotFound;
}

7-12 排序

#include<stdio.h>
#include<stdlib.h>

int cmp(const void* a,const void* b)
{
    return (*(int*)a-*(int*)b);
}

int a[100004];
int main()
{
    int x;
    scanf("%d",&x);
    for(int i=0;i<x;i++)
    {
        scanf("%d",&a[i]);
    }
    
    qsort(a,x,sizeof(int),cmp);
    for(int j=0;j<x;j++)
    {
        if(j!=0)
            printf(" ");
        printf("%d",a[j]);
    }
}

6-2 顺序表操作集

#include <stdio.h>
#include <stdlib.h>

#define MAXSIZE 5
#define ERROR -1
typedef enum {false, true} bool;
typedef int ElementType;
typedef int Position;
typedef struct LNode *List;
struct LNode {
    ElementType Data[MAXSIZE];
    Position Last; /* 保存线性表中最后一个元素的位置 */
};

List MakeEmpty(); 
Position Find( List L, ElementType X );
bool Insert( List L, ElementType X, Position P );
bool Delete( List L, Position P );

int main()
{
    List L;
    ElementType X;
    Position P;
    int N;

    L = MakeEmpty();
    scanf("%d", &N);
    while ( N-- ) {
        scanf("%d", &X);
        if ( Insert(L, X, 0)==false )
            printf(" Insertion Error: %d is not in.\n", X);
    }
    scanf("%d", &N);
    while ( N-- ) {
        scanf("%d", &X);
        P = Find(L, X);
        if ( P == ERROR )
            printf("Finding Error: %d is not in.\n", X);
        else
            printf("%d is at position %d.\n", X, P);
    }
    scanf("%d", &N);
    while ( N-- ) {
        scanf("%d", &P);
        if ( Delete(L, P)==false )
            printf(" Deletion Error.\n");
        if ( Insert(L, 0, P)==false )
            printf(" Insertion Error: 0 is not in.\n");
    }
    return 0;
}

List MakeEmpty()
{
    List p;
    p = (List)malloc(sizeof(struct LNode));
    p->Last = -1;
    return p;
}
Position Find( List L, ElementType X )
{
    for(int i=0;i<=L->Last;i++)
    {
        if(L->Data[i] == X) return i;
    }
    return ERROR;
}
bool Insert( List L, ElementType X, Position P )
{
    if(L->Last == MAXSIZE-1) 
    {
        printf("FULL");
        return false;
    }
    
    if(P<0 || P>L->Last+1)
    {
        printf("ILLEGAL POSITION");
        return false;
    }

    L->Last++;
    for(int i=L->Last;i>=P+1;i--)
    {
        L->Data[i] = L->Data[i-1];
    }

    L->Data[P] = X;
    return true;
}
bool Delete( List L, Position P )
{
    if(P<0 || P>L->Last )
    {
        printf("POSITION %d EMPTY",P);
        return false;
    }
    
    if(L->Last ==0)
    {
        L->Last--;
        return true;
    }

    for(int i=P;i<=L->Last-1;i++)
    {
        L->Data[i] = L->Data[i+1];
    }
    L->Last--;
    return true;
}

6-3 求链式表的表长

int Length( List L )
{
    List p = L;
    int ccount = 0;
    while(p)
    {
        ccount++;
        p = p->Next;
    }
    return ccount;
}

6-4 查找链表第k个数

ElementType FindKth( List L, int K )
{
    List p = L;
    while(K && p)
    {
        K--;
        if(K==0) return p->Data;
        p = p->Next;
    }
    return ERROR;

}