BZOJ 1260: [CQOI2007]涂色paint 区间DP

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 100, M = 30005, mod = 1e9+9, inf = 0x3f3f3f3f;
typedef long long ll;

int dp[N][N];
char s[M];
int dfs(int l,int r) {
    if(l==r) return 1;
    int& ans = dp[l][r];
    if(ans) return ans;
    ans = r-l+1;
    if(s[l]==s[l+1]) return ans = dfs(l+1,r);
    if(s[r]==s[r-1]) return ans = dfs(l,r-1);
    if(s[l]==s[r]) return ans = min(dfs(l+1,r),dfs(l,r-1));
    for(int i=l;i<r;i++)
        ans = min(ans,dfs(l,i)+dfs(i+1,r));
    return ans;
}
int main() {
    scanf("%s",s);
    int n = strlen(s)-1;
    printf("%d\n",dfs(0,n));
    return 0;
}