feat: solve No.2391

Author: BaffinLee

2301-2400/2391. Minimum Amount of Time to Collect Garbage.md

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+# 2391. Minimum Amount of Time to Collect Garbage
+
+- Difficulty: Medium.
+- Related Topics: Array, String, Prefix Sum.
+- Similar Questions: .
+
+## Problem
+
+You are given a **0-indexed** array of strings `garbage` where `garbage[i]` represents the assortment of garbage at the `ith` house. `garbage[i]` consists only of the characters `'M'`, `'P'` and `'G'` representing one unit of metal, paper and glass garbage respectively. Picking up **one** unit of any type of garbage takes `1` minute.
+
+You are also given a **0-indexed** integer array `travel` where `travel[i]` is the number of minutes needed to go from house `i` to house `i + 1`.
+
+There are three garbage trucks in the city, each responsible for picking up one type of garbage. Each garbage truck starts at house `0` and must visit each house **in order**; however, they do **not** need to visit every house.
+
+Only **one** garbage truck may be used at any given moment. While one truck is driving or picking up garbage, the other two trucks **cannot** do anything.
+
+Return** the **minimum** number of minutes needed to pick up all the garbage.**
+
+ 
+Example 1:
+
+```
+Input: garbage = ["G","P","GP","GG"], travel = [2,4,3]
+Output: 21
+Explanation:
+The paper garbage truck:
+1. Travels from house 0 to house 1
+2. Collects the paper garbage at house 1
+3. Travels from house 1 to house 2
+4. Collects the paper garbage at house 2
+Altogether, it takes 8 minutes to pick up all the paper garbage.
+The glass garbage truck:
+1. Collects the glass garbage at house 0
+2. Travels from house 0 to house 1
+3. Travels from house 1 to house 2
+4. Collects the glass garbage at house 2
+5. Travels from house 2 to house 3
+6. Collects the glass garbage at house 3
+Altogether, it takes 13 minutes to pick up all the glass garbage.
+Since there is no metal garbage, we do not need to consider the metal garbage truck.
+Therefore, it takes a total of 8 + 13 = 21 minutes to collect all the garbage.
+```
+
+Example 2:
+
+```
+Input: garbage = ["MMM","PGM","GP"], travel = [3,10]
+Output: 37
+Explanation:
+The metal garbage truck takes 7 minutes to pick up all the metal garbage.
+The paper garbage truck takes 15 minutes to pick up all the paper garbage.
+The glass garbage truck takes 15 minutes to pick up all the glass garbage.
+It takes a total of 7 + 15 + 15 = 37 minutes to collect all the garbage.
+```
+
+ 
+**Constraints:**
+
+
+	
+- `2 <= garbage.length <= 105`
+	
+- `garbage[i]` consists of only the letters `'M'`, `'P'`, and `'G'`.
+	
+- `1 <= garbage[i].length <= 10`
+	
+- `travel.length == garbage.length - 1`
+	
+- `1 <= travel[i] <= 100`
+
+
+
+## Solution
+
+```javascript
+/**
+ * @param {string[]} garbage
+ * @param {number[]} travel
+ * @return {number}
+ */
+var garbageCollection = function(garbage, travel) {
+    var res = 0;
+    var m = 0;
+    var p = 0;
+    var g = 0;
+    for (var i = 0; i < garbage.length; i++) {
+        const num = count(garbage[i]);
+        m += (travel[i - 1] || 0);
+        p += (travel[i - 1] || 0);
+        g += (travel[i - 1] || 0);
+        if (num.m) {
+            res += m + num.m;
+            m = 0;
+        }
+        if (num.p) {
+            res += p + num.p;
+            p = 0;
+        }
+        if (num.g) {
+            res += g + num.g;
+            g = 0;
+        }
+    }
+    return res;
+};
+
+var count = function(str) {
+    var res = { m: 0, p: 0, g: 0 };
+    for (var i = 0; i < str.length; i++) {
+        if (str[i] === 'M') {
+            res.m++;
+        } else if (str[i] === 'P') {
+            res.p++;
+        } else {
+            res.g++;
+        }
+    }
+    return res;
+};
+```
+
+**Explain:**
+
+nope.
+
+**Complexity:**
+
+* Time complexity : O(n * m).
+* Space complexity : O(1).