HDU 2476 String painter（区间DP）

区间DP，dp[i][j][k]表示染色区间i，j当前颜色为k（0,表示无色）的最小代价，然后记忆化搜索进行转移即可

代码：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int N = 105;
const int INF = 0x3f3f3f3f;

char a[N], b[N];
int dp[N][N][N], n;

int dfs(int l, int r, int c) {
	int &ans = dp[l][r][c];
	if (ans != -1) return ans;
	ans = INF;
	if (l > r) return ans = 0;
	if (!c && a[l] == b[l]) ans = min(ans, dfs(l + 1, r, c));
	if (c && b[c] == b[l]) ans = min(ans, dfs(l + 1, r, c));
 	for (int i = l; i <= r; i++)
	 	ans = min(ans, dfs(l + 1, i, l) + dfs(i + 1, r, c) + 1);	
 	return ans;
}

int main() {
	while (gets(a + 1) != NULL) {
		gets(b + 1);
		n = strlen(a + 1);
		memset(dp, -1, sizeof(dp));
		printf("%d\n", dfs(1, n, 0));
 	}
	return 0;
}