# Shrinking

## 题目描述

Snuke can change a string $t$ of length $N$ into a string $t’$ of length $N-1$ under the following rule:

• for each $i \; (1 \le i \le N-1)$, the $i$-th character of $t’$ must be either the $i$-th or $(i+1)$-th character of $t$.

There is a string $s$ consisting of lowercase English letters. Snuke’s objective is to apply the above operation to $s$ repeatedly so that all the characters in $s$ are the same. Find the minimum necessary number of operations.

## 题意概述

$$\forall i \in [1, len-1], \; s_i’=s_i \lor s_i’=s_{i+1}$$

## 代码

#include <iostream>
using namespace std;
string s;
int len, last[26], a[26], ans;
int main()
{
cin >> s;
len = ans = s.length();
for (int i = 0; i < len; ++i) {
a[s[i] - 'a'] = max(a[s[i] - 'a'], i - last[s[i] - 'a']);
last[s[i] - 'a'] = i + 1;
}
for (int i = 0; i < 26; ++i) {
ans = min(ans, max(a[i], len - last[i]));
}
cout << ans << endl;
return 0;
}


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