u

2026-07-03 10:27:25 +08:00
parent 4850991edd
commit a01ef32bf7
4 changed files with 247 additions and 0 deletions
@@ -0,0 +1,53 @@
+package top100liked
+
+import (
+	"fmt"
+	"testing"
+)
+
+// https://leetcode.cn/problems/combination-sum/?envType=study-plan-v2&envId=top-100-liked
+
+func combinationSum(candidates []int, target int) [][]int {
+	res := [][]int{}
+	sum := 0
+	r := []int{}
+
+	var helper func(strat int)
+	helper = func(start int) {
+		for i := start; i < len(candidates); i++ {
+			v := candidates[i]
+			if sum+v == target {
+				cp := make([]int, len(r))
+				copy(cp, r)
+				cp = append(cp, v)
+				res = append(res, cp)
+				continue
+			} else if sum+v < target {
+				r = append(r, v)
+				sum += v
+				helper(i)
+				sum -= v
+				r = r[:len(r)-1]
+			}
+		}
+	}
+
+	helper(0)
+	return res
+}
+
+func Test(t *testing.T) {
+	fmt.Printf("%+v\n", combinationSum([]int{2, 3, 6, 7}, 7))
+}
+
+func Test2(t *testing.T) {
+	fmt.Printf("%+v\n", combinationSum([]int{2, 3, 5}, 8))
+}
+
+func Test3(t *testing.T) {
+	fmt.Printf("%+v\n", combinationSum([]int{2}, 1))
+}
+
+func Test4(t *testing.T) {
+	fmt.Printf("%+v\n", combinationSum([]int{4, 2, 8}, 8))
+}
@@ -0,0 +1,48 @@
+package top100liked
+
+import (
+	"fmt"
+	"testing"
+)
+
+// https://leetcode.cn/problems/generate-parentheses/description/?envType=study-plan-v2&envId=top-100-liked
+
+func generateParenthesis(n int) []string {
+	res := []string{}
+	r := []byte{}
+	num_l := 0
+	num_r := 0
+
+	var helper func()
+	helper = func() {
+		if num_l < n {
+			r = append(r, '(')
+			num_l++
+			helper()
+			num_l--
+			r = r[:len(r)-1]
+		}
+		if num_l > num_r {
+			r = append(r, ')')
+			num_r++
+			helper()
+			num_r--
+			r = r[:len(r)-1]
+		}
+		if num_l == n && num_r == n {
+			res = append(res, string(r))
+		}
+	}
+
+	helper()
+
+	return res
+}
+
+func Test(t *testing.T) {
+	fmt.Printf("%+v\n", generateParenthesis(3))
+}
+
+func Test2(t *testing.T) {
+	fmt.Printf("%+v\n", generateParenthesis(1))
+}
@@ -0,0 +1,92 @@
+package top100liked
+
+import (
+	"fmt"
+	"slices"
+	"testing"
+)
+
+// https://leetcode.cn/problems/word-search/description/?envType=study-plan-v2&envId=top-100-liked
+
+func exist(board [][]byte, word string) bool {
+	w := []byte(word)
+	l := len(word)
+	m := len(board)
+	n := len(board[0])
+	// 下、右、上、左
+	move := [4][2]int{{1, 0}, {0, 1}, {-1, 0}, {0, -1}}
+
+	// 减枝让耗时降低了很多
+
+	var boardCnt [128]int // 覆盖 ASCII，字母在范围内
+	for _, row := range board {
+		for _, c := range row {
+			boardCnt[c]++
+		}
+	}
+
+	var wordCnt [128]int
+	for _, c := range w {
+		wordCnt[c]++
+	}
+
+	// 字符频次可行性预检。 扫一遍 board 统计各字符计数，若 word 中某字符出现次数超过 board 上的数量，直接 return false。
+	for _, char := range w {
+		if boardCnt[char] < wordCnt[char] {
+			return false
+		}
+	}
+
+	// 词序翻转剪枝（算法层面最大收益）。 统计 board 中 word[0] 和 word[l-1] 的出现次数，若首字符比尾字符更常见，就把 word 反转后再搜——从稀有端开始DFS，能在更浅层就剪掉大量无效分支。
+	if boardCnt[0] > boardCnt[len(boardCnt)-1] {
+		slices.Reverse(w)
+	}
+
+	var helper func(idx, row, col int) bool
+	helper = func(idx, row, col int) bool {
+		for _, v := range move {
+			new_row := row + v[0]
+			new_col := col + v[1]
+			if new_row >= 0 && new_row < m && new_col >= 0 && new_col < n && w[idx] == board[new_row][new_col] {
+				if idx == l-1 {
+					return true
+				}
+				board[new_row][new_col] = '#'
+				if helper(idx+1, new_row, new_col) {
+					return true
+				}
+				board[new_row][new_col] = w[idx]
+			}
+		}
+		return false
+	}
+
+	for i, row := range board {
+		for j, col := range row {
+			if col == w[0] {
+				if l == 1 {
+					return true
+				}
+				board[i][j] = '#'
+				if helper(1, i, j) {
+					return true
+				}
+				board[i][j] = w[0]
+			}
+		}
+	}
+
+	return false
+}
+
+func Test(t *testing.T) {
+	fmt.Printf("%+v\n", exist([][]byte{{'A', 'B', 'C', 'E'}, {'S', 'F', 'C', 'S'}, {'A', 'D', 'E', 'E'}}, "ABCCED"))
+}
+
+func Test2(t *testing.T) {
+	fmt.Printf("%+v\n", exist([][]byte{{'A', 'B', 'C', 'E'}, {'S', 'F', 'C', 'S'}, {'A', 'D', 'E', 'E'}}, "SEE"))
+}
+
+func Test3(t *testing.T) {
+	fmt.Printf("%+v\n", exist([][]byte{{'A', 'B', 'C', 'E'}, {'S', 'F', 'C', 'S'}, {'A', 'D', 'E', 'E'}}, "ABCB"))
+}
@@ -0,0 +1,54 @@
+package top100liked
+
+import (
+	"fmt"
+	"testing"
+)
+
+// https://leetcode.cn/problems/palindrome-partitioning/description/?envType=study-plan-v2&envId=top-100-liked
+
+func partition(s string) [][]string {
+	res := [][]string{}
+	path := []string{}
+	// 动态规划，降低查找回文串的时间复杂度
+	dp := make([][]bool, len(s))
+	for i := range len(s) {
+		dp[i] = make([]bool, len(s))
+		dp[i][i] = true
+	}
+	for length := 2; length <= len(s); length++ {
+		for i := 0; i+length <= len(s); i++ {
+			j := i + length - 1
+			dp[i][j] = (s[i] == s[j]) && (length <= 2 || dp[i+1][j-1])
+		}
+	}
+
+	var helper func(start int)
+	helper = func(start int) {
+		if start == len(s) {
+			cp := make([]string, len(path))
+			copy(cp, path)
+			res = append(res, cp)
+			return
+		}
+		for end := start; end < len(s); end++ {
+			if dp[start][end] {
+				path = append(path, s[start:end+1])
+				helper(end + 1)
+				path = path[:len(path)-1]
+			}
+		}
+	}
+
+	helper(0)
+
+	return res
+}
+
+func Test(t *testing.T) {
+	fmt.Printf("%+v\n", partition("aab"))
+}
+
+func Test2(t *testing.T) {
+	fmt.Printf("%+v\n", partition("a"))
+}