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关于本题思路及OJ系统的若干疑问

Posted by xiao1590 at 2007-02-17 20:08:01 on Problem 1159
1。为什么用GCC提交比C快得多?所有的问题都是这样吗?
2。关于DP算法的问题,这个题卡了我太久时间,脑子都晕了,不明白DP所省掉的重叠的问题是哪写?
3。本人菜鸟,各位毋见笑
代码如下:
#include<stdio.h>

char word[5001];
short int save[5001][5001];

int min(int a,int b)
{
	if (a<b)
		return a;
	else
		return b;
}

int pal(int a,int b)
{
	if (save[a][b]>-1)//DP算法的核心就是这句话
		return save[a][b];//DP算法的核心就是这句话
	if (a==b)
	{
		save[a][b]=0;
		return 0;
	}
	if (word[a]==word[b])
	{
		if (a+1==b)
		{
			save[a][b]=0;
			return 0;
		}
		else
			save[a][b]=pal(a+1,b-1);
	}
	else
	{
		save[a][b]=pal(a+1,b);
		if (pal(a,b-1)<save[a][b])
			save[a][b]=save[a][b-1];
		save[a][b]++;
		return save[a][b];
	}
}

void main()
{
	int len,i,j;
	while (scanf("%d",&len)!=EOF)
	{
		scanf("%s",word);
		for (i=0;i<len;i++)
			for (j=0;j<len;j++)
				save[i][j]=-1;
		printf("%d\n",pal(0,len-1));
	}
}

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