日期:2014-05-20  浏览次数:20724 次

一个简单的算法题(杭电ACM Problem10003)
下面是我的答案,提交后OJ给了我个Time Limit Exceeded,求各位大侠看看能不能给精简下。谢谢各位哥哥姐姐了。(注:开始的数组定义不能改)
Java code
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int num = 0;
        int max, sum, index, startIndex, endIndex;
        int array[] = new int[100000];
        num = scanner.nextInt();
        for (int i = 1; i <= num; i++) {
            max = 0;
            index = 0;
            startIndex = 1;
            endIndex = 1;
            sum = 0;
            while (scanner.hasNext()) {
                array[index] = scanner.nextInt();
                index++;
                if (array[0] == (index - 1))
                    break;
            }
            max = array[1];
            for (int j = 1; j <= array[0]; j++) {
                sum = 0;
                for (int m = j; m <= array[0]; m++) {
                    sum = sum + array[m];
                    if (max <= sum) {
                        max = sum;
                        startIndex = j;
                        endIndex = m;
                    }
                }
            }
            System.out.println("Case " + i + ":");
            System.out.println(max + " " + startIndex + " " + endIndex);
            if (i != num) {
                System.out.println();
            }
        }
    }
}


------解决方案--------------------
这题要用DP(动态规划)

你的算法时间复杂度为O(n^2)

N最大为100000.你的复杂度为10^10

那面的测评机器10^9大约为1s.

你肯定超时了。


我写过一个C++的代码。
看代码估计你也理解不了。
去查一个解题报告吧。

C/C++ code

#include <iostream>
#define N 100001
using namespace std;

int main()
{
    int t,t1;
    cin >> t;
    t1 = t;
    while ( t-- ) {
        int m, i, f[N], n[N], l[N], max = 0, left = 1, right = 1;
        cin >> m;
        for ( i = 0; i < m; i++) {
            cin >> n[i];
        }
        f[0] = n[0];
        l[0] = 0;
        for ( i = 1; i < m; i++) {
            if( 0 > f[i-1] ) {
                f[i] = n[i];
                l[i] = i;
            } else {
                f[i] = f[i-1] + n[i];
                l[i] = l[i-1];
            }
        }
        for ( i = 1,max = f[0]; i < m; i++) {
                if( f[i] > max) {
                    max = f[i];
                    left = l[i] + 1;
                    right = i + 1;
                }
        }
        cout <<"Case "<<t1 - t<<":"<<endl;
        cout << max <<" "<< left <<" "<< right <<endl;
        if(t != 0 ) {
            cout << endl;
        }


    }
    return 0;
}