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60 lines
3.7 KiB
HTML
60 lines
3.7 KiB
HTML
<p>You are given a string <code>s</code>. <code>s[i]</code> is either a lowercase English letter or <code>'?'</code>.</p>
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<p>For a string <code>t</code> having length <code>m</code> containing <strong>only</strong> lowercase English letters, we define the function <code>cost(i)</code> for an index <code>i</code> as the number of characters <strong>equal</strong> to <code>t[i]</code> that appeared before it, i.e. in the range <code>[0, i - 1]</code>.</p>
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<p>The <strong>value</strong> of <code>t</code> is the <strong>sum</strong> of <code>cost(i)</code> for all indices <code>i</code>.</p>
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<p>For example, for the string <code>t = "aab"</code>:</p>
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<ul>
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<li><code>cost(0) = 0</code></li>
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<li><code>cost(1) = 1</code></li>
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<li><code>cost(2) = 0</code></li>
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<li>Hence, the value of <code>"aab"</code> is <code>0 + 1 + 0 = 1</code>.</li>
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</ul>
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<p>Your task is to <strong>replace all</strong> occurrences of <code>'?'</code> in <code>s</code> with any lowercase English letter so that the <strong>value</strong> of <code>s</code> is <strong>minimized</strong>.</p>
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<p>Return <em>a string denoting the modified string with replaced occurrences of </em><code>'?'</code><em>. If there are multiple strings resulting in the <strong>minimum value</strong>, return the <span data-keyword="lexicographically-smaller-string">lexicographically smallest</span> one.</em></p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
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<p><strong>Input: </strong> <span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;"> s = "???" </span></p>
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<p><strong>Output: </strong> <span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;"> "abc" </span></p>
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<p><strong>Explanation: </strong> In this example, we can replace the occurrences of <code>'?'</code> to make <code>s</code> equal to <code>"abc"</code>.</p>
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<p>For <code>"abc"</code>, <code>cost(0) = 0</code>, <code>cost(1) = 0</code>, and <code>cost(2) = 0</code>.</p>
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<p>The value of <code>"abc"</code> is <code>0</code>.</p>
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<p>Some other modifications of <code>s</code> that have a value of <code>0</code> are <code>"cba"</code>, <code>"abz"</code>, and, <code>"hey"</code>.</p>
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<p>Among all of them, we choose the lexicographically smallest.</p>
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</div>
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<p><strong class="example">Example 2:</strong></p>
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<div class="example-block" style="border-color: var(--border-tertiary); border-left-width: 2px; color: var(--text-secondary); font-size: .875rem; margin-bottom: 1rem; margin-top: 1rem; overflow: visible; padding-left: 1rem;">
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<p><strong>Input: </strong> <span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">s = "a?a?"</span></p>
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<p><strong>Output: </strong> <span class="example-io" style="font-family: Menlo,sans-serif; font-size: 0.85rem;">"abac"</span></p>
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<p><strong>Explanation: </strong> In this example, the occurrences of <code>'?'</code> can be replaced to make <code>s</code> equal to <code>"abac"</code>.</p>
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<p>For <code>"abac"</code>, <code>cost(0) = 0</code>, <code>cost(1) = 0</code>, <code>cost(2) = 1</code>, and <code>cost(3) = 0</code>.</p>
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<p>The value of <code>"abac"</code> is <code>1</code>.</p>
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</div>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 <= s.length <= 10<sup>5</sup></code></li>
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<li><code>s[i]</code> is either a lowercase English letter or <code>'?'</code>.</li>
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</ul>
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