From 281ae8befc870970ca9c7ea7c7f2298c38942ea7 Mon Sep 17 00:00:00 2001 From: hechenghao Date: Mon, 21 Oct 2024 13:14:29 +0800 Subject: [PATCH] add no.134 answer --- leetcode/0134.Gas-Station/Gas.go | 26 ++++++++ leetcode/0134.Gas-Station/Gas_test.go | 47 ++++++++++++++ leetcode/0134.Gas-Station/README.md | 88 +++++++++++++++++++++++++++ 3 files changed, 161 insertions(+) create mode 100644 leetcode/0134.Gas-Station/Gas.go create mode 100644 leetcode/0134.Gas-Station/Gas_test.go create mode 100644 leetcode/0134.Gas-Station/README.md diff --git a/leetcode/0134.Gas-Station/Gas.go b/leetcode/0134.Gas-Station/Gas.go new file mode 100644 index 000000000..4277a791c --- /dev/null +++ b/leetcode/0134.Gas-Station/Gas.go @@ -0,0 +1,26 @@ +package leetcode + +func canCompleteCircuit(gas []int, cost []int) int { + totalGas := 0 + totalCost := 0 + currGas := 0 + start := 0 + + for i := 0; i < len(gas); i++ { + totalGas += gas[i] + totalCost += cost[i] + currGas += gas[i] - cost[i] + + if currGas < 0 { + start = i + 1 + currGas = 0 + } + } + + if totalGas < totalCost { + return -1 + } + + return start + +} diff --git a/leetcode/0134.Gas-Station/Gas_test.go b/leetcode/0134.Gas-Station/Gas_test.go new file mode 100644 index 000000000..f6c2a7893 --- /dev/null +++ b/leetcode/0134.Gas-Station/Gas_test.go @@ -0,0 +1,47 @@ +package leetcode + +import ( + "fmt" + "testing" +) + +type question134 struct { + para134 + ans134 +} + +// para 是参数 +// one 代表第一个参数 +type para134 struct { + one []int + two []int +} + +// ans 是答案 +// one 代表第一个答案 +type ans134 struct { + one int +} + +func Test_Problem134(t *testing.T) { + qs := []question134{ + + { + para134{[]int{1, 2, 3, 4, 5}, []int{3, 4, 5, 1, 2}}, + ans134{3}, + }, + + { + para134{[]int{2, 3, 4}, []int{3, 4, 3}}, + ans134{-1}, + }, + } + + fmt.Printf("------------------------Leetcode Problem 134------------------------\n") + + for _, q := range qs { + _, p := q.ans134, q.para134 + fmt.Printf("【input】:%v, %v 【output】:%v\n", p.one, p.two, canCompleteCircuit(p.one, p.two)) + } + fmt.Printf("\n\n\n") +} diff --git a/leetcode/0134.Gas-Station/README.md b/leetcode/0134.Gas-Station/README.md new file mode 100644 index 000000000..e4cb07821 --- /dev/null +++ b/leetcode/0134.Gas-Station/README.md @@ -0,0 +1,88 @@ +# [134. Gas Stations](https://leetcode.com/problems/gas-station/) + + +## 题目 + +You are given a list of gas stations on a circular route, where the amount of gas at station i is gas[i], and the cost to travel from station i to its next station (i+1) is cost[i]. You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from station i to its next station (i+1). You begin the journey with an empty tank at one of the gas stations. + +Write a function that returns the starting gas station's index if you can travel around the circuit once in the clockwise direction, otherwise return -1. If there exists a solution, it is guaranteed to be unique. + +**Example 1:** + +``` +Input: gas = [1,2,3,4,5], cost = [3,4,5,1,2] +Output: 3 +Explanation: Start at station 3 (index 3), you have 4 liters of gas. Now you have a total of =0+4=4 liters of gas. +Travel to station 4. Now you have 4 - 1 + 5 = 8 liters of gas. +Travel to station 0. Now you have 8 - 2 + 1 = 7 liters of gas. +Travel to station 1. Now you have 7 - 3 + 2 = 6 liters of gas. +Travel to station 2. Now you have 6 - 4 + 3 = 5 liters of gas. +Travel to station 3 again. This time you will have consumed 5 liters of gas, which is exactly enough for you to return to station 3. +Therefore, 3 can be the starting index. +``` + +**Example 2:** + +``` +Input: gas = [2,3,4], cost = [3,4,3] +Output: -1 +Explanation: You cannot start at station 0 or 1 because there is not enough gas to get you to the next station. +We start at station 2, we get 4 liters of gas. Now you have a total of =0+4=4 liters of gas. +Travel to station 0. Now you have 4 - 3 + 2 = 3 liters of gas. +Travel to station 1. Now you have 3 - 3 + 3 = 3 liters of gas. +You cannot return to station 2 because it requires 4 liters of gas but you only have 3 liters in your tank. +Therefore, no matter what, you cannot travel around the ring. +``` + +**Constraints:** + +- `gas.length == n` +- `cost.length == n` +- `1 <= n <= 10^5` +- `0 <= gas[i], cost[i] <= 10^4` + +## 题目大意 + +在一条环路上有 n 个加油站,其中第 i 个加油站有汽油 gas[i] 升。 + +你有一辆油箱容量无限的的汽车,从第 i 个加油站开往第 i+1 个加油站需要消耗汽油 cost[i] 升。你从其中的一个加油站出发,开始时油箱为空。 + +给定两个整数数组 gas 和 cost ,如果你可以按顺序绕环路行驶一周,则返回出发时加油站的编号,否则返回 -1 。如果存在解,则 保证 它是 唯一 的。 + +## 解题思路 + +- 初始化总油量(totalGas)和总消耗(totalCost)为0,起始点(start)为0,当前油量(currGas)为0。 + 遍历每个加油站,累加油量和消耗,计算当前油量。 + 如果当前油量小于0,说明从上一个加油站到当前加油站的油量不足以到达下一个加油站,因此将起始点设置为当前加油站的下一个位置,并将当前油量重置为0。 + 遍历结束后,如果总油量小于总消耗,说明无法完成整个旅程,返回-1;否则返回起始点。 + +## 代码 + +```go +package leetcode + +func canCompleteCircuit(gas []int, cost []int) int { + totalGas := 0 + totalCost := 0 + currGas := 0 + start := 0 + + for i := 0; i < len(gas); i++ { + totalGas += gas[i] + totalCost += cost[i] + currGas += gas[i] - cost[i] + + if currGas < 0 { + start = i + 1 + currGas = 0 + } + } + + if totalGas < totalCost { + return -1 + } + + return start +} + +``` \ No newline at end of file