2010-5-25 Maximum Sum
Maximum Sum
今天有些无聊，就跑到jude online 上做做题，选的题目是 ：
Maximum Sum
Time Limit: 15 Sec Memory Limit: 128 MB
Submissions: 523 Solved: 41
Description
Given an integer array, how will you find out the increasing subsequence which gives the largest sum. For example,
4, 2, 1, 5, 3
in this subsequence a few possible increasing subsequences are
1) 4
2) 2
3) 1
4) 5
5) 3
6) 4, 5
7) 2, 5
8) 2, 3
9) 1, 5
10) 1, 3
but 4, 5 gievs the maximum sum.
Your task is how to find such the maximum sum in a given integer array.
Input
Multiply Cases, For each case:
The first line contains N(0< N <=1000000), which is the number of the integer array.
The second line contains N integer numbers not exceeding 2000000 by the absolute value.
Output
For each case, output only one integer, which is the maximum sum of increasing subsequences.
Sample Input
5
4 2 1 5 3
Sample Output
9
写完后，修改了几次，每次都是超时，有些郁闷，不过欣慰的是 至少做对了，只是速度太慢了，我最后的代码如下：
#include <stdio.h>
#define N 1000000
int main(){
int n = 0, i = 0, j = 0;
int data[N], rec[N], tmp = 0, max, maxn;
scanf("%d", &n);
for(;i < n;i++){
scanf("%d", &data[i]);
rec[i] = data[i];
}
max = rec[0];
maxn = 0;
for(i = 1; i <n; i ++){
for(j = i -1 ; j >= 0; j --){
if(data[j] < data[i]){
if(j == maxn){
rec[i] = max + data[i];
max = rec[i];
maxn = i;
goto out;
}
else{
if((tmp = rec[j] + data[i]) > rec[i]){
rec[i] = tmp;
}
}
}
}
if(rec[i] > max){
max = rec[i];
maxn = i;
}
out: ;
}
printf("%d", max);
return 0;
}
希望高手看到后可以指点下，谢啦！