HDOJ 1003Max Sum (dp)

This is original link to the problem

this question is a typical dp problem .It’s need us to find the maximum sub region sum,and I tear apart the equation of dp to find the start point and terminate point .

#include<bits/stdc++.h>#include <cstring>#define maxn 100005int dp[maxn];int num[maxn];int st[maxn];int en[maxn];using namespace std;int T=0;void islast(int t){    if(t!=T)    {        printf("\n");    }}int main(){    scanf("%d",&T);    for(int t=1;t<=T;t++)    {        memset(dp,0,sizeof(dp));        memset(en,0,sizeof(en));        memset(st,0,sizeof(st));        int n=0;        int cnt=0,minus_n = -99999999,minus_index;        scanf("%d",&n);        for(int i=1;i<=n;i++)        {            scanf("%d",&num[i]);            if(num[i]<0)            {                cnt++;                if(minus_n < num[i])                {                    minus_index = i;                    minus_n = num[i];                }            }        }        if(cnt==n)        {            printf("Case %d:\n",t);            printf("%d %d %d\n",minus_n,minus_index,minus_index);            islast(t);            continue;        }        dp[1] = num[1];        en[1] = st[1] = 1;        int ans=-1,index;        for(int i=2;i<=n;i++)        {            //dp[i] = max(dp[i-1],0)+num[i];            if(dp[i-1]>=0)            {                dp[i] = num[i]+dp[i-1];                en[i] = i;                st[i] = st[i-1];            }            else            {                dp[i] = num[i];                st[i] = en[i] = i;            }            if(ans < dp[i])            {                ans = dp[i];                index = i;            }        }        /*for(int i=0;i<=n;i++)        {            cout<<dp[i]<<" "<<st[i]<<" "<<en[i]<<endl;        }*/        printf("Case %d:\n",t);        printf("%d %d %d\n",ans,st[index],en[index]);        islast(t);        //cout<<ans<<" "<<st[index]<<" "<<en[index]<<endl;        //cout<<dp[n]<<" "<<st[n]<<" "<<en[n]<<endl;    }    return 0;}