Problem Description
Given a sequence a[1],a[2],a[3]......a[n], your job is to calculate the max sum of a sub-sequence. For example, given (6,-1,5,4,-7), the max sum in this sequence is 6 + (-1) + 5 + 4 = 14.
Input
The first line of the input contains an integer T(1<=T<=20) which means the number of test cases. Then T lines follow, each line starts with a number N(1<=N<=100000), then N integers followed(all the integers are between -1000 and 1000).
Output
For each test case, you should output two lines. The first line is "Case #:", # means the number of the test case. The second line contains three integers, the Max Sum in the sequence, the start position of the sub-sequence, the end position of the sub-sequence.
If there are more than one result, output the first one. Output a blank line between two cases.
Sample Input
2
5 6 -1 5 4 -7
7 0 6 -1 1 -6 7 -5
Sample Output
Case 1:
14 1 4
Case 2:
7 1 6
思路:對於每一個當前點都保證相加之後的和比本身大就好了,貪心思想。如果用我註釋掉的方法做超時,但目前還沒想到怎麼優化,歡迎評論|“_”|
代碼如下:
#include<iostream>
#include<stdio.h>
#define M 100000+5
#define LL long long
using namespace std;
//int a[M];
int main(){
int t,ans=0;
while(scanf("%d", &t)!=EOF){
while(t--){
int n,st=1,ed=1,est=1;
int sum,x,maxn;
scanf("%d%d", &n, &x);
sum=maxn=x;
for(int i=2; i<=n; ++i){
scanf("%d", &x);
if(sum+x<x){
sum=x;
st=i;
}
else{
sum+=x;
}
if(maxn<sum){
maxn=sum;
est=st;
ed=i;
}
}
/*for(int i=1; i<=n; ++i){//超時
if(a[i]<=0) continue;
for(int j=i,k; j<=n ; ++j){
//int k;
s=0;
for(k=1; k<=j; ++k){
s+=a[k];
if(sum<s){
sum=s;
st=i;
ed=k;
}
}
}
}*/
if(ans!=0) printf("\n");
printf("Case %d:\n%d %d %d\n",++ans, maxn, est, ed);
}
}
return 0;
}