1. 程式人生 > >POJ 1003 Max Sum

POJ 1003 Max Sum

元素 integer [1] bsp more nta rip tle int

Max Sum

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 代碼如下: 原理:找出最大串的方法:和並法。遍歷的同時將前面的加起來,具體看代碼(AC)
#include<stdio.h>
#include
<string.h> int main() { int t,num=0;; scanf("%d",&t); while(t--) { num++; int n,temp=1,a;//temp表示當前最大區間開頭所在位置,一開始假定為1 scanf("%d",&n); int start=1,max=-1001,end1,sum=0; for(int i=0;i<n;i++) { scanf("%d"
,&a);//a就是區間元素了,由於只用一次,所以就不用數組浪費內存了 sum+=a; if(sum>max)//max 表示目前為止最大區間的和,sum大於max,說明區間改變 { max=sum; end1=i+1; start=temp; } if(sum<0)//sum小於0,則表示若前面的temp為開頭,不會有最大區間,故將sum,temp重置。 { sum
=0;//sum=0表示重新開始計算最大區間(下面的也是這個意思) temp=i+2; } } printf("Case %d:\n%d %d %d\n",num,max,start,end1); if(t!=0) printf("\n"); } return 0; }

POJ 1003 Max Sum