4,5,10,11,15,17

Author: xiaof-github

alg/2021/leetcode/10-1.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+    "fmt"
+)
+
+func main() {
+    fmt.Println(isMatch("aab", "c*a*b"))
+}
+
+func isMatch(s string, p string) bool {
+    arr1 := []byte(s)
+    arr2 := []byte(p)
+
+    dfs := make([][]int, len(arr1)+1)
+
+    for i := 0; i < len(arr1)+1; i++ {
+        tmp := make([]int, len(arr2)+1)        
+        dfs[i] = tmp
+    }
+
+    return compare(arr1, arr2, dfs, 0, 0)
+}
+
+func compare(s []byte, p []byte, dfs [][]int, i int, j int) bool {
+    if dfs[i][j] != 0 {
+        return dfs[i][j] == 1
+    }
+    len1 := len(s)
+    len2 := len(p)
+    flag := false
+    if j == len2 {
+        if i == len1 {
+            flag = true
+        }
+    }
+
+    if j == len2-1 {
+        if i < len1 {
+            if s[i] == p[j] || p[j] == byte('.') {
+                flag = compare(s, p, dfs, i+1, j+1)
+            }
+        }
+    }
+
+    if j < len2-1 {
+        if i < len1 && (s[i] == p[j] || p[j] == byte('.')) {            
+            if p[j+1] == byte('*') {
+                flag = compare(s, p, dfs, i, j+2) || compare(s, p, dfs, i+1, j) || compare(s, p, dfs, i+1, j+2)
+            } else {
+                flag = compare(s, p, dfs, i+1, j+1)
+            }
+        } else {
+            if p[j+1] == byte('*') {
+                flag = compare(s, p, dfs, i, j+2)
+            }
+        }        
+    }
+
+    if flag == true {
+        dfs[i][j] = 1
+    } else {
+        dfs[i][j] = -1
+
+    }
+    return flag
+}

alg/2021/leetcode/10.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+    fmt.Println(isMatch("fs", ".*.."))
+}
+
+func isMatch(s string, p string) bool {
+    arr1 := []byte(s)
+    arr2 := []byte(p)    
+
+    return compare(arr1, arr2)
+}
+
+func compare(s []byte , p []byte) bool {
+    len1 := len(s)
+    len2 := len(p)
+
+    if len2 == 0 {
+        return len1 == 0
+    }
+
+    if len1 >= 1 {
+        matched := (s[0] == p[0] || p[0] == byte('.'))
+                    
+        if matched {
+            if len2 >= 2 && p[1] == byte('*') {
+                return compare(s, p[2:]) || compare(s[1:], p)
+            } else {
+                return compare(s[1:], p[1:])
+            }
+        } else {            
+            if len2 >= 2 && p[1] == byte('*') {
+                return compare(s, p[2:])
+            } else {
+                return false
+            }
+        }        
+        
+    } else if len2 >= 2{
+        if p[1] == byte('*') {
+            return compare(s, p[2:])
+        }        
+    }    
+
+    return false
+        
+}

alg/2021/leetcode/11-1.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+    arr := []int{2,3,3,4,8,9,9,1}
+    fmt.Println(maxArea(arr))
+}
+
+func maxArea(height []int) int {
+    max := 0
+    rst := 0
+    a := 0
+    j := len(height) - 1
+    for i:=0;;{        
+        a = height[i]
+        if a > height[j] {
+            a = height[j]
+        }
+
+        rst = a*(j-i)
+        if max < rst {
+            max = rst
+        }
+        if height[i] < height[j] {
+            i++
+        } else {
+            j--
+        }
+        if i==j {
+            break
+        }
+    }   
+
+    return max
+}

alg/2021/leetcode/11.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+    arr := []int{2,3,3,4,8,9,9,1}
+    fmt.Println(maxArea(arr))
+}
+
+func maxArea(height []int) int {
+    max := 0
+    a := 0
+    for i:=0;i<len(height);i++{        
+        for j:=i+1;j<len(height);j++ {
+            a = height[i]
+            if height[i] > height[j] {
+                a = height[j]
+            }
+            rst := a * (j-i)
+            if max < rst {
+                max = rst
+            }
+        }
+    }   
+
+    return max
+}

alg/2021/leetcode/15.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	arr := []int{-4, -2, 0, 2, 3, 221, 23, 45, 63, 38, 2, 32, 5, 6}
+
+	fmt.Println(threeSum(arr))
+}
+
+/**
+ * 排序。双指针移动。
+ */
+func threeSum(nums []int) [][]int {
+	if len(nums) < 3 {
+		return make([][]int, 0)
+	}
+	rst := make([][]int, 0)
+
+	fastSort(nums, 0, len(nums)-1)
+
+	for i := 0; i < len(nums); i++ {
+		if nums[i] > 0 {
+			break
+		}
+		if i >= 1 && nums[i] == nums[i-1] {
+			continue
+		}
+		left := i + 1
+		right := len(nums) - 1
+		lastLeft := left
+		lastRight := right
+		for left < right {
+			if left != lastLeft && nums[left] == nums[lastLeft] {
+				left++
+				continue
+			}
+			if right != lastRight && nums[right] == nums[lastRight] {
+				right--
+				continue
+			}
+
+			// 满足条件时，left和right同时滑动
+			if nums[i]+nums[left]+nums[right] == 0 {
+				add := make([]int, 0)
+				add = append(add, nums[i], nums[left], nums[right])
+				rst = append(rst, add)
+				lastLeft = left
+				lastRight = right
+				left++
+				right--
+			} else if nums[i]+nums[left]+nums[right] > 0 {
+				// 右滑
+				lastRight = right
+				right--
+
+			} else {
+				// 左滑
+				lastLeft = left
+				left++
+			}
+		}
+	}
+	return rst
+}
+
+func fastSort(arr []int, left int, right int) {
+	if left >= right {
+		return
+	}
+	l1 := left
+	r1 := right
+	middle := arr[left]
+
+	for left != right {
+
+		for right > left && arr[right] >= middle {
+			right--
+		}
+		arr[left] = arr[right]
+		for left < right && arr[left] <= middle {
+			left++
+		}
+		arr[right] = arr[left]
+	}
+	arr[left] = middle
+	fastSort(arr, l1, left-1)
+	fastSort(arr, left+1, r1)
+
+}

alg/2021/leetcode/17.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"fmt"
+)
+
+var rst []string
+
+func main() {
+    str := "623"   
+    // rst = append(rst, "abc")
+    // fmt.Println(rst[0])
+    fmt.Println(letterCombinations(str))
+}
+
+
+func letterCombinations(digits string) []string {
+    if digits == "" {
+        return make([]string, 0)
+    }
+    rst = make([]string, 0)
+    mapd := map[string][]string{"2":{"a","b","c"}, "3":{"d","e","f"},"4":{"g","h","i"},"5":{"j","k","l"}, "6":{"m","n","o"}, "7":{"p","q","r","s"}, "8":{"t","u","v"},"9":{"w","x","y","z"}}      
+    // fmt.Println(mapd)
+
+    slice := make([][]string, 0)
+    for i:=0;i<len(digits);i++{
+        a := mapd[string(digits[i])]
+        slice = append(slice, a)
+    }
+    // fmt.Println(slice)
+    // fmt.Println(digits[2:3])
+    // fmt.Println(string(digits[2]))
+    // fmt.Println([]rune(digits))
+    backTrace(slice, 0, "")
+    return rst
+}
+
+/*
+ * go语言字符串操作： https://www.jianshu.com/p/61dc40f5090d
+ * 回溯法，回溯所有组合
+*/
+func backTrace(slice [][]string, layer int, base string) {
+
+    if layer == len(slice) - 1 {        
+        for i:=0;i<len(slice[layer]);i++{
+            tmp := base + string(slice[layer][i])
+            rst = append(rst, tmp)
+            // fmt.Println(rst)
+        }
+    } else {
+        for i:=0;i<len(slice[layer]);i++ {
+            backTrace(slice, layer+1, base+string(slice[layer][i]))
+        }
+    }
+}