CF1114D 【Flood Fill】

Solution

一看就是很水的区间DP

(dp[i][j])表示区间([l,r])都涂成同色的代价。
(dp[i][j] = min( dp[i][j], dp[i][k] + dp[k][j] + 1))

#include<bits/stdc++.h>
using namespace std;
int n, x, a[5010], f[5010][5010], y, cnt;
int main() {
	scanf("%d", &n);
	for (int i = 1; i <= n; i ++) {
		scanf("%d", &x);
		if (x != y) a[++ cnt] = x;
		y = x;
	}
	for (int i = 1; i <= cnt; i ++)
		for (int j = 1; j + i <= cnt; j ++)
			if (a[j] == a[j + i])
				f[j][j + i] = f[j + 1][j + i - 1] + 1;
			else f[j][j + i] = std::min(f[j + 1][j + i], f[j][j + i - 1]) + 1;
	return printf("%d
", f[1][cnt]), 0;
}