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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Koko Eating Bananas - LeetCode 875</title>
<link rel="stylesheet" href="styles.css">
<script src="https://d3js.org/d3.v7.min.js"></script>
</head>
<body>
<div class="container">
<div class="problem-info">
<h1><span class="problem-number">#875</span> Koko Eating Bananas 🍌</h1>
<p>Koko wants to eat all bananas before guards return. Find the minimum eating speed. Binary search on the answer!</p>
<div class="problem-meta">
<span class="meta-tag">🔍 Binary Search</span>
<span class="meta-tag">🔢 Array</span>
<span class="meta-tag">⏱️ O(n log m)</span>
</div>
<div class="file-ref">
📄 Python: <a href="../python/0875_koko_eating_bananas/0875_koko_eating_bananas.py">0875_koko_eating_bananas.py</a>
</div>
</div>
<div class="explanation-panel">
<h4>💡 How It Works (Layman's Terms)</h4>
<ul>
<li><strong>Problem:</strong> Koko needs to eat all bananas before guards return in h hours</li>
<li><strong>Each hour:</strong> She picks one pile and eats k bananas (or all if less than k)</li>
<li><strong>Goal:</strong> Find minimum speed k that lets her finish in time</li>
<li><strong>Binary search on speed:</strong> Speed can be 1 to max(piles)</li>
<li><strong>For each pile:</strong> Hours = ceil(pile / speed)</li>
<li><strong>If total hours ≤ h:</strong> Speed is fast enough, try slower</li>
<li><strong>If total hours > h:</strong> Too slow, need faster speed</li>
</ul>
</div>
<div class="visualization-section">
<h3>🎬 Step-by-Step Visualization</h3>
<div class="controls">
<button class="btn btn-primary" id="stepBtn" onclick="step()">Step</button>
<button class="btn btn-success" id="autoBtn" onclick="toggleAuto()">Auto Run</button>
<button class="btn btn-warning" onclick="reset()">Reset</button>
</div>
<div class="info-box">
⏰ Guards return in h = 8 hours
</div>
<div class="status-message" id="statusMessage">
Click "Step" or "Auto Run" to find Koko's minimum eating speed
</div>
<div class="variable-display">
<div class="variable-box">
<div class="variable-name">Speed Range</div>
<div class="variable-value" id="rangeVal">1 - 11</div>
</div>
<div class="variable-box">
<div class="variable-name">Test Speed (k)</div>
<div class="variable-value" id="speedVal">-</div>
</div>
<div class="variable-box">
<div class="variable-name">Hours Needed</div>
<div class="variable-value" id="hoursVal">-</div>
</div>
<div class="variable-box">
<div class="variable-name">Can Finish?</div>
<div class="variable-value" id="canFinishVal">-</div>
</div>
</div>
<div class="array-section">
<div class="array-label">Banana Piles:</div>
<div class="array-container" id="pilesContainer"></div>
</div>
<div class="array-section">
<div class="array-label">Hours per pile at current speed:</div>
<div class="array-container" id="hoursContainer"></div>
</div>
<div class="info-box" id="resultBox" style="display: none;"></div>
</div>
<div class="code-section">
<h3>💻 Python Solution</h3>
<div class="code-block">
<pre>from typing import List
import math
"""
LeetCode Koko Eating Bananas
Problem from LeetCode: https://leetcode.com/problems/koko-eating-bananas/
Description:
Koko loves to eat bananas. There are n piles of bananas, the ith pile has piles[i] bananas. The guards have gone and will come back in h hours.
Koko can decide her bananas-per-hour eating speed of k. Each hour, she chooses some pile of bananas and eats k bananas from that pile. If the pile has less than k bananas, she eats all of them instead and will not eat any more bananas during this hour.
Koko likes to eat slowly but still wants to finish eating all the bananas before the guards return.
Return the minimum integer k such that she can eat all the bananas within h hours.
Example 1:
Input: piles = [3,6,7,11], h = 8
Output: 4
Example 2:
Input: piles = [30,11,23,4,20], h = 5
Output: 30
Example 3:
Input: piles = [30,11,23,4,20], h = 6
Output: 23
Constraints:
1 <= piles.length <= 10^4
piles.length <= h <= 10^9
1 <= piles[i] <= 10^9
"""
class Solution:
def min_eating_speed(self, piles: List[int], h: int) ->int:
"""
Find the minimum eating speed k such that Koko can eat all the bananas within h hours.
Args:
piles: List of banana piles where piles[i] represents the number of bananas in the ith pile
h: The maximum number of hours Koko can take to eat all bananas
Returns:
int: The minimum integer k such that Koko can eat all the bananas within h hours
"""
left = 1
right = max(piles)
while left < right:
mid = (left + right) // 2
if self._can_finish(piles, mid, h):
right = mid
else:
left = mid + 1
return left
def _can_finish(self, piles: List[int], speed: int, h: int) ->bool:
"""
Check if Koko can eat all bananas within h hours at the given speed.
Args:
piles: List of banana piles
speed: Eating speed (bananas per hour)
h: Maximum hours allowed
Returns:
bool: True if Koko can finish all bananas within h hours, False otherwise
"""
hours = 0
for pile in piles:
hours += math.ceil(pile / speed)
if hours > h:
return False
return True
def minEatingSpeed_alt(self, piles: List[int], h: int) ->int:
"""
Alternative implementation with a different binary search approach.
Args:
piles: List of banana piles
h: Maximum hours allowed
Returns:
int: The minimum eating speed required
"""
left = 1
right = max(piles)
result = right
while left <= right:
mid = (left + right) // 2
hours = sum(math.ceil(pile / mid) for pile in piles)
if hours <= h:
result = min(result, mid)
right = mid - 1
else:
left = mid + 1
return result
if __name__ == '__main__':
# Example usage based on LeetCode sample
solution = Solution()
# Example 1
piles1 = [3, 6, 7, 11]
h1 = 8
result1 = solution.min_eating_speed(piles1, h1)
print(f"Example 1: {result1}") # Expected: 4
# Example 2
piles2 = [30, 11, 23, 4, 20]
h2 = 5
result2 = solution.min_eating_speed(piles2, h2)
print(f"Example 2: {result2}") # Expected: 30
# Example 3
piles3 = [30, 11, 23, 4, 20]
h3 = 6
result3 = solution.min_eating_speed(piles3, h3)
print(f"Example 3: {result3}") # Expected: 23
</pre>
</div>
</div>
</div>
<script>
const piles = [3, 6, 7, 11];
const h = 8;
let left = 1;
let right = Math.max(...piles);
let currentSpeed = -1;
let phase = 'init';
let autoInterval = null;
function init() {
left = 1;
right = Math.max(...piles);
currentSpeed = -1;
renderPiles();
document.getElementById('hoursContainer').innerHTML = '<span style="color: #999;">Select a speed to calculate...</span>';
document.getElementById('rangeVal').textContent = `${left} - ${right}`;
document.getElementById('speedVal').textContent = '-';
document.getElementById('hoursVal').textContent = '-';
document.getElementById('canFinishVal').textContent = '-';
document.getElementById('resultBox').style.display = 'none';
}
function renderPiles() {
const container = document.getElementById('pilesContainer');
container.innerHTML = '';
piles.forEach((pile, idx) => {
const box = document.createElement('div');
box.className = 'array-box';
box.style.background = '#fff8e1';
box.style.borderColor = '#ffc107';
box.innerHTML = `🍌 ${pile}<span class="index-label">pile ${idx + 1}</span>`;
container.appendChild(box);
});
}
function calculateHours(speed) {
return piles.map(pile => Math.ceil(pile / speed));
}
function renderHours(speed) {
const container = document.getElementById('hoursContainer');
container.innerHTML = '';
const hoursPerPile = calculateHours(speed);
hoursPerPile.forEach((hours, idx) => {
const box = document.createElement('div');
box.className = 'array-box';
box.style.background = '#e3f2fd';
box.style.borderColor = '#2196f3';
box.innerHTML = `${hours}h<span class="index-label">⌈${piles[idx]}/${speed}⌉</span>`;
container.appendChild(box);
});
// Total
const total = hoursPerPile.reduce((a, b) => a + b, 0);
const totalBox = document.createElement('div');
totalBox.className = 'array-box';
totalBox.style.background = total <= h ? '#e8f5e9' : '#ffebee';
totalBox.style.borderColor = total <= h ? '#4caf50' : '#f44336';
totalBox.style.fontWeight = 'bold';
totalBox.innerHTML = `= ${total}h<span class="index-label">total</span>`;
container.appendChild(totalBox);
}
function step() {
if (phase === 'init') {
phase = 'searching';
document.getElementById('statusMessage').textContent =
'Binary search for minimum speed between 1 and max(piles)...';
}
if (phase === 'searching') {
if (left >= right) {
phase = 'done';
document.getElementById('resultBox').style.display = 'block';
document.getElementById('resultBox').className = 'info-box secondary';
document.getElementById('resultBox').textContent = `✅ Minimum speed: ${left} bananas/hour`;
document.getElementById('statusMessage').textContent =
`Found! Koko needs to eat at least ${left} bananas per hour to finish in ${h} hours.`;
document.getElementById('stepBtn').disabled = true;
stopAuto();
return;
}
currentSpeed = Math.floor((left + right) / 2);
const hoursNeeded = calculateHours(currentSpeed).reduce((a, b) => a + b, 0);
const canFinish = hoursNeeded <= h;
document.getElementById('rangeVal').textContent = `${left} - ${right}`;
document.getElementById('speedVal').textContent = currentSpeed;
document.getElementById('hoursVal').textContent = `${hoursNeeded} / ${h}`;
document.getElementById('canFinishVal').textContent = canFinish ? '✅ Yes' : '❌ No';
document.getElementById('canFinishVal').style.color = canFinish ? '#4caf50' : '#f44336';
renderHours(currentSpeed);
if (canFinish) {
document.getElementById('statusMessage').textContent =
`Speed ${currentSpeed}: ${hoursNeeded} hours ≤ ${h} hours ✓ Try slower! right = ${currentSpeed}`;
right = currentSpeed;
} else {
document.getElementById('statusMessage').textContent =
`Speed ${currentSpeed}: ${hoursNeeded} hours > ${h} hours ✗ Too slow! left = ${currentSpeed + 1}`;
left = currentSpeed + 1;
}
}
}
function toggleAuto() {
if (autoInterval) {
stopAuto();
} else {
document.getElementById('autoBtn').textContent = 'Pause';
autoInterval = setInterval(() => {
if (phase === 'done') {
stopAuto();
} else {
step();
}
}, 1500);
}
}
function stopAuto() {
if (autoInterval) {
clearInterval(autoInterval);
autoInterval = null;
}
document.getElementById('autoBtn').textContent = 'Auto Run';
}
function reset() {
stopAuto();
phase = 'init';
document.getElementById('stepBtn').disabled = false;
document.getElementById('statusMessage').textContent =
'Click "Step" or "Auto Run" to find Koko\'s minimum eating speed';
init();
}
init();
</script>
</body>
</html>