程序员面试题精选100题(61)-数对之差的最大值

// 程序员面试题精选100题(61)-数对之差的最大值.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <iostream>using namespace std;#define N 9int max(int a,int b,int c){if (a>b){if (a>c){return a;}elsereturn c;}else{if (b>c){return b;}elsereturn c;}}int divided(int *arr,int i,int j)//divide and conquer method from i to j {if (i==j){return 0;}int mid=(i+j)/2;// into i==0 j==0 wrongint m1,m2,m3;m1=divided(arr,i,mid);m2=divided(arr,mid+1,j);//mid + 1int temp1=-1000,temp2=1000;for (int k=i;k<=mid;k++){if (arr[k]>temp1){temp1=arr[k];}}for (int k2=mid;k2<=j;k2++){if (arr[k2]<temp2){temp2=arr[k2];}}m3=temp1-temp2;return max(m1,m2,m3);}int sumOfArr(int* arr,int n){int *diff = new int[n-1];for (int i=0;i<n-1;i++){diff[i]=arr[i]-arr[i+1];}int max=diff[0];for (int j=1;j<n-1;j++){if (diff[j-1]+diff[j]>diff[j]){diff[j]=diff[j-1]+diff[j];}if (max<diff[j]){max=diff[j];}}return max;}int dynamicP(int* arr, int n){int *diff=new int[n];//diff[i]是以数组中第i个数字为减数的所有数对之差的最大值diff[1]=arr[0]-arr[1];int max=diff[1];for (int i=2;i<n;i++){if (diff[i-1]+arr[i-1]-arr[i]>arr[i-1]-arr[i]){diff[i]=diff[i-1]+arr[i-1]-arr[i];}elsediff[i]=arr[i-1]-arr[i];if (max<diff[i]){max=diff[i];}}return max;}int _tmain(int argc, _TCHAR* argv[]){int arr[]={20,-4,12,10,16,-7,5,1,9};int (*diff)[N] = new int[N-1][N];// how to create dynamic arrayint maxv=0;for (int i=0;i<N-1;i++){diff[i][i+1]=arr[i]-arr[i+1];if (diff[i][i+1]>maxv){maxv=diff[i][i+1];}}cout<<"when step is "<<1<<" max is "<<maxv<<endl;int stepnum=N-1;for (int step=2;step<=stepnum;step++){for (int j=0;j<N-step;j++){diff[j][j+step]=diff[j][j+1]+diff[j+1][j+step];if (diff[j][j+step]>maxv){maxv=diff[j][j+step];}}cout<<"when step is "<<step<<" max is "<<maxv<<endl;}cout<<"dynamic programming with two dimensions array is "<<maxv<<endl;//////////////////////////////////////////////////////////////////////////cout<<"divide and conquer method is "<<divided(arr,0,N-1)<<endl;//////////////////////////////////////////////////////////////////////////cout<<"sum of the sub array method is "<<sumOfArr(arr,N)<<endl;//////////////////////////////////////////////////////////////////////////cout<<"dynamic programming with one dimensions array is "<<dynamicP(arr,N)<<endl;system("pause");return 0;}