HDU1003MAX SUM (动态规划求最大子序列的和)
Max Sum
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 206582 Accepted Submission(s):
48294
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
Author
Ignatius.L
Recommend
题意:求连续子序列和的最大值。
题解: 注意这道题要求是输出第一个符合条件的序列,而且存在负数,样例之间要用空行分隔。
#include <bits/stdc++.h> using namespace std; const int maxn=1e5+5; int a[maxn],n; int main() { int t,cas=1; scanf("%d",&t); while(t--) { scanf("%d",&n); int sum=0,ans=-1005; int s=1,e=1,k=1; for(int i=1;i<=n;i++) { scanf("%d",&a[i]); sum+=a[i]; if(sum>ans) { s=k; e=i; ans=sum; } if(sum<0) //0的意义就是这段数做的是负功 { sum=0; k=i+1; } } printf("Case %d:\n",cas++); printf("%d %d %d\n",ans,s,e); if(t>0) puts(""); } return 0; }
#include <bits/stdc++.h> using namespace std; const int N=1e5+5; int a[N],n; int main() { int t,cas=1; cin>>t; while(t--) { cin>>n; int sum=0,mx=-1005,s=1,e=1,ts=1; for(int i=1;i<=n;i++) { cin>>a[i]; sum+=a[i]; if(sum>mx) { mx=sum; s=ts; e=i; } if(sum<0) { sum=0; ts=i+1; } } printf("Case %d:\n",cas++); printf("%d %d %d\n",mx,s,e); if(t) printf("\n"); } return 0; } /* 100 2 1 2 1 1 3 -1 1 2 2 -7 3 */
牢记顺序是 加 大于 小于!!