题目连接：http://codeforces.com/contest/1132/problem/F
You are given a string ss of length nn consisting of lowercase Latin letters. You may apply some operations to this string: in one operation you can delete some contiguous substring of this string, if all letters in the substring you delete are equal. For example, after deleting substring bbbb from string abbbbaccdd we get the string aaccdd.
Calculate the minimum number of operations to delete the whole string ss.
Input
The first line contains one integer nn (1≤n≤5001≤n≤500) — the length of string ss.
The second line contains the string ss (|s|=n|s|=n) consisting of lowercase Latin letters.
Output
Output a single integer — the minimal number of operation to delete string ss.
Examples
input
Copy
5 abaca
output
Copy
3
input
Copy
8 abcddcba
output
Copy
4
题意： 给你一个只包含小写字符的字符串，你可以删除连续相同的一段字符，问最少需要几次操作完全删除这个字符串
#include<cstdio>
#include<algorithm>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<cmath>
#include<vector>
#include<cstring>
#include<string>
#include<iostream>
#include<iomanip>
#define mset(a,b) memset(a,b,sizeof(a))
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
//const ll mod=1e9+7;
const int N=1000000;
const int inf=0x3f3f3f3f;
//priority_queue<int,vector<int>,greater<int> >q;
char s[505];
int dp[505][505];
int main()
{
int n;
while(~scanf("%d",&n))
{
scanf("%s",s);
for(int i=0;i<n;i++)
dp[i][i]=1;
for(int len=1;len<=n;len++)
{
for(int i=0,j=len;i<=n,j<=n;i++,j++)
{
if(s[i]==s[j])//如果i和j的字母相同
dp[i][j]=dp[i+1][j-1]+1;
else//不相同
dp[i][j]=min(dp[i][j-1],dp[i+1][j])+1;
for(int k=i;k<=j;k++)
{
dp[i][j]=min(dp[i][j],dp[i][k]+dp[k][j]-1);
}
}
}
printf("%d\n",dp[0][n-1]);
}
return 0;
}