
4. 选择正整数l,r (1&lt;=l&lt;=r&lt;=n)，将X_l,X_{l+1},...,X_r都减去b。<br />
求最少的操作次数将{X_i}全部变成0</span></p>
<p></p></div></div></div></div><div class="row"><div class="column"><h4 class="ui top attached block header">输入格式</h4><div class="ui bottom attached segment font-content"><div style="position: relative; overflow: hidden;"><div class=content><p><span style="font-size: medium"><br />
第一行三个正整数n,a,b (n&lt;=100,000, a,b&lt;=10^9)。<br />
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