UVa 10617 Again Palindromes / 记忆化搜索

#include <stdio.h>
#include <string.h>
long long dp[70][70];
char a[70];
long long n;

long long dfs(long long l,long long r)
{
	if(l > r)
		return 0;
	if(l == r)
		return 1;
	if(dp[l][r] != -1)
		return dp[l][r];
	long long ret = 0;
	if(a[l] == a[r])
	{
		ret = dfs(l+1,r) + dfs(l,r-1) + 1;
		//ret = dfs(l+1,r) + dfs(l,r-1) - dfs(l+1,r-1)+ dfs(l+1,r-1) + 1;
	}
	else
	{		
		ret = dfs(l+1,r) + dfs(l,r-1) - dfs(l+1,r-1);
	}
	dp[l][r] = ret;
	return ret; 
}
int main()
{
	long long t;
	scanf("%lld",&t);
	while(t--)
	{
		scanf("%s",a+1);
		n = strlen(a+1);		
		memset(dp,-1,sizeof(dp));
		printf("%lld\n",dfs(1,n));
	}
	return 0;
}