1.算法基本思想
分治法求最大子段和:利用分治算法先劃分為若幹個子問題,遞歸求解每一個子問題,最後将子問題合并,進而求解到整個問題的解。
2.主要資料結構及其作用
一維數組:存儲并記錄資料
3.測試用例:
4.實驗結果截圖:
測試用例1
測試用例2
測試用例3
5.代碼實作
#include<iostream>
using namespace std;
int besti,bestj;
int MaxSubSum(int *a,int left,int right)
{
int sum=0;
if(left==right){
sum=a[left]>0?a[left]:0;
besti=left;
bestj=right;
}
else
{
int center=(left+right)/2;
int leftsum=MaxSubSum(a,left,center);
int rightsum=MaxSubSum(a,center+1,right);
int s1=0;int lefts=0;
for(int i=center; i>=left; i--)
{
lefts+=a[i];
if(lefts>s1){
s1=lefts;
besti=i;
}
}
int s2=0;int rights=0;
for(int i=center+1; i<=right; i++)
{
rights+=a[i];
if(rights>s2){
s2=rights;
bestj=i;
}
}
sum=s1+s2;
if(sum<leftsum)sum=leftsum;
if(sum<rightsum)sum=rightsum;
}
return sum;
}
int main()
{
int n;
cout<<"請輸入需要輸入的元素的個數:"<<endl;
cin>>n;
int a[n];
cout<<"請輸入"<<n<<"個元素:"<<endl;
for(int i=0; i<n; i++)
cin>>a[i];
cout<<"最大子段和為:"<<MaxSubSum(a, 0, n-1)<<" ";
cout<<"起始下标:"<<besti+1<<"終止下标:"<<bestj+1<<endl;
}