feat: update solutions to lc problems: No.0034,1870,1894

* No.0034.Find First and Last Position of Element in Sorted Array
* No.1870.Minimum Speed to Arrive on Time
* No.1894.Find the Student that Will Replace the Chalk

Author: yanglbme

solution/0000-0099/0034.Find First and Last Position of Element in Sorted Array/README.md

@@ -49,9 +49,9 @@
 
 **方法一：二分查找**
 
-两遍二分，分别查找出左边界和右边界。
+我们可以进行两次二分查找，分别查找出左边界和右边界。
 
-时间复杂度 $O(\log n)$。其中 $n$ 为数组长度。
+时间复杂度 $O(\log n)$，空间复杂度 $O(1)$。其中 $n$ 是数组 `nums` 的长度。
 
 以下是二分查找的两个通用模板：
 
@@ -189,23 +189,12 @@ var searchRange = function (nums, target) {
 
 ```go
 func searchRange(nums []int, target int) []int {
-    search := func(x int) int {
-        left, right := 0, len(nums)
-        for left < right {
-            mid := (left + right) >> 1
-            if nums[mid] >= x {
-                right = mid
-            } else {
-                left = mid + 1
-            }
-        }
-        return left
-    }
-    l, r := search(target), search(target+1)
-    if l == r {
-        return []int{-1, -1}
-    }
-    return []int{l, r - 1}
+	l := sort.Search(len(nums), func(i int) bool { return nums[i] >= target })
+	r := sort.Search(len(nums), func(i int) bool { return nums[i] > target })
+	if l == r {
+		return []int{-1, -1}
+	}
+	return []int{l, r - 1}
 }
 ```
 

solution/0000-0099/0034.Find First and Last Position of Element in Sorted Array/README_EN.md

@@ -154,23 +154,12 @@ var searchRange = function (nums, target) {
 
 ```go
 func searchRange(nums []int, target int) []int {
-    search := func(x int) int {
-        left, right := 0, len(nums)
-        for left < right {
-            mid := (left + right) >> 1
-            if nums[mid] >= x {
-                right = mid
-            } else {
-                left = mid + 1
-            }
-        }
-        return left
-    }
-    l, r := search(target), search(target+1)
-    if l == r {
-        return []int{-1, -1}
-    }
-    return []int{l, r - 1}
+	l := sort.Search(len(nums), func(i int) bool { return nums[i] >= target })
+	r := sort.Search(len(nums), func(i int) bool { return nums[i] > target })
+	if l == r {
+		return []int{-1, -1}
+	}
+	return []int{l, r - 1}
 }
 ```
 

solution/0000-0099/0034.Find First and Last Position of Element in Sorted Array/Solution.go

@@ -1,17 +1,6 @@
 func searchRange(nums []int, target int) []int {
-	search := func(x int) int {
-		left, right := 0, len(nums)
-		for left < right {
-			mid := (left + right) >> 1
-			if nums[mid] >= x {
-				right = mid
-			} else {
-				left = mid + 1
-			}
-		}
-		return left
-	}
-	l, r := search(target), search(target+1)
+	l := sort.Search(len(nums), func(i int) bool { return nums[i] >= target })
+	r := sort.Search(len(nums), func(i int) bool { return nums[i] > target })
 	if l == r {
 		return []int{-1, -1}
 	}

solution/1800-1899/1870.Minimum Speed to Arrive on Time/README.md

@@ -70,6 +70,8 @@
 
 二分枚举速度值，找到满足条件的最小速度。
 
+时间复杂度 $O(n\times \log m)$，其中 $n$ 和 $m$ 分别为数组 `dist` 和最大速度值。
+
 以下是二分查找的两个通用模板：
 
 模板 1：
@@ -245,28 +247,22 @@ function arriveOnTime(dist, speed, hour) {
 ```go
 func minSpeedOnTime(dist []int, hour float64) int {
 	n := len(dist)
-	left, right := 1, int(1e7)
-	check := func(speed float64) bool {
+	const mx int = 1e7 + 1
+	x := sort.Search(mx, func(s int) bool {
+		if s == 0 {
+			return false
+		}
 		var cost float64
 		for _, v := range dist[:n-1] {
-			cost += math.Ceil(float64(v) / speed)
+			cost += math.Ceil(float64(v) / float64(s))
 		}
-		cost += float64(dist[n-1]) / speed
+		cost += float64(dist[n-1]) / float64(s)
 		return cost <= hour
-
-	}
-	for left < right {
-		mid := (left + right) >> 1
-		if check(float64(mid)) {
-			right = mid
-		} else {
-			left = mid + 1
-		}
-	}
-	if check(float64(left)) {
-		return left
+	})
+	if x < 0 || x == mx {
+		return -1
 	}
-	return -1
+	return x
 }
 ```
 

solution/1800-1899/1870.Minimum Speed to Arrive on Time/README_EN.md

@@ -222,28 +222,22 @@ function arriveOnTime(dist, speed, hour) {
 ```go
 func minSpeedOnTime(dist []int, hour float64) int {
 	n := len(dist)
-	left, right := 1, int(1e7)
-	check := func(speed float64) bool {
+	const mx int = 1e7 + 1
+	x := sort.Search(mx, func(s int) bool {
+		if s == 0 {
+			return false
+		}
 		var cost float64
 		for _, v := range dist[:n-1] {
-			cost += math.Ceil(float64(v) / speed)
+			cost += math.Ceil(float64(v) / float64(s))
 		}
-		cost += float64(dist[n-1]) / speed
+		cost += float64(dist[n-1]) / float64(s)
 		return cost <= hour
-
-	}
-	for left < right {
-		mid := (left + right) >> 1
-		if check(float64(mid)) {
-			right = mid
-		} else {
-			left = mid + 1
-		}
-	}
-	if check(float64(left)) {
-		return left
+	})
+	if x < 0 || x == mx {
+		return -1
 	}
-	return -1
+	return x
 }
 ```
 

solution/1800-1899/1870.Minimum Speed to Arrive on Time/Solution.go

@@ -1,25 +1,19 @@
 func minSpeedOnTime(dist []int, hour float64) int {
 	n := len(dist)
-	left, right := 1, int(1e7)
-	check := func(speed float64) bool {
+	const mx int = 1e7 + 1
+	x := sort.Search(mx, func(s int) bool {
+		if s == 0 {
+			return false
+		}
 		var cost float64
 		for _, v := range dist[:n-1] {
-			cost += math.Ceil(float64(v) / speed)
+			cost += math.Ceil(float64(v) / float64(s))
 		}
-		cost += float64(dist[n-1]) / speed
+		cost += float64(dist[n-1]) / float64(s)
 		return cost <= hour
-
-	}
-	for left < right {
-		mid := (left + right) >> 1
-		if check(float64(mid)) {
-			right = mid
-		} else {
-			left = mid + 1
-		}
-	}
-	if check(float64(left)) {
-		return left
+	})
+	if x < 0 || x == mx {
+		return -1
 	}
-	return -1
+	return x
 }

solution/1800-1899/1894.Find the Student that Will Replace the Chalk/README.md

@@ -176,16 +176,7 @@ func chalkReplacer(chalk []int, k int) int {
 		s[i+1] = s[i] + chalk[i]
 	}
 	k %= s[n]
-	left, right := 0, n-1
-	for left < right {
-		mid := (left + right) >> 1
-		if s[mid+1] > k {
-			right = mid
-		} else {
-			left = mid + 1
-		}
-	}
-	return left
+	return sort.Search(n, func(i int) bool { return s[i+1] > k })
 }
 ```
 

solution/1800-1899/1894.Find the Student that Will Replace the Chalk/README_EN.md

@@ -119,16 +119,7 @@ func chalkReplacer(chalk []int, k int) int {
 		s[i+1] = s[i] + chalk[i]
 	}
 	k %= s[n]
-	left, right := 0, n-1
-	for left < right {
-		mid := (left + right) >> 1
-		if s[mid+1] > k {
-			right = mid
-		} else {
-			left = mid + 1
-		}
-	}
-	return left
+	return sort.Search(n, func(i int) bool { return s[i+1] > k })
 }
 ```
 

solution/1800-1899/1894.Find the Student that Will Replace the Chalk/Solution.go

@@ -5,14 +5,5 @@ func chalkReplacer(chalk []int, k int) int {
 		s[i+1] = s[i] + chalk[i]
 	}
 	k %= s[n]
-	left, right := 0, n-1
-	for left < right {
-		mid := (left + right) >> 1
-		if s[mid+1] > k {
-			right = mid
-		} else {
-			left = mid + 1
-		}
-	}
-	return left
+	return sort.Search(n, func(i int) bool { return s[i+1] > k })
 }