Merge pull request #1033 from chengleqi/master

update 0051.N皇后.md Go版本

problems/0051.N皇后.md

@@ -346,70 +346,57 @@ class Solution {
 
 ### Go 
 ```Go
-import "strings"
+func solveNQueens(n int) [][]string {
     var res [][]string
-
+	chessboard := make([][]string, n)
-func isValid(board [][]string, row, col int) (res bool){
+	for i := 0; i < n; i++ {
-    n := len(board)
+		chessboard[i] = make([]string, n)
-    for i:=0; i < row; i++ {
-        if board[i][col] == "Q" {
-            return false
-        }
 	}
 	for i := 0; i < n; i++ {
-        if board[row][i] == "Q" {
+		for j := 0; j < n; j++ {
-            return false
+			chessboard[i][j] = "."
 		}
 	}
-
+	var backtrack func(int)
-    for i ,j := row, col; i >= 0 && j >=0 ; i, j = i - 1, j- 1{
+	backtrack = func(row int) {
-        if board[i][j] == "Q"{
+		if row == n {
-            return false
+			temp := make([]string, n)
-        }
+			for i, rowStr := range chessboard {
-    }
+				temp[i] = strings.Join(rowStr, "")
-    for i, j := row, col; i >=0 && j < n; i,j = i-1, j+1 {
-        if board[i][j] == "Q" {
-            return false
-        }
-    }
-    return true
-}
-
-func backtrack(board [][]string, row int) {
-    size := len(board)
-    if row == size{
-        temp := make([]string, size)
-        for i := 0; i<size;i++{
-            temp[i] = strings.Join(board[i],"")
 			}
 			res = append(res, temp)
 			return
 		}
-    for col := 0; col < size; col++ {
-        if !isValid(board, row, col){
-            continue
-        }
-        board[row][col] = "Q"
-        backtrack(board, row+1)
-        board[row][col] = "."
-    }
-}
-
-func solveNQueens(n int) [][]string {
-    res = [][]string{}
-    board := make([][]string, n)
 		for i := 0; i < n; i++ {
-        board[i] = make([]string, n)
+			if isValid(n, row, i, chessboard) {
-    }
+				chessboard[row][i] = "Q"
-    for i := 0; i < n; i++{
+				backtrack(row + 1)
-        for j := 0; j<n;j++{
+				chessboard[row][i] = "."
-            board[i][j] = "."
 			}
 		}
-    backtrack(board, 0)
+	}
-
+	backtrack(0)
 	return res
 }
+
+func isValid(n, row, col int, chessboard [][]string) bool {
+	for i := 0; i < row; i++ {
+		if chessboard[i][col] == "Q" {
+			return false
+		}
+	}
+	for i, j := row-1, col-1; i >= 0 && j >= 0; i, j = i-1, j-1 {
+		if chessboard[i][j] == "Q" {
+			return false
+		}
+	}
+	for i, j := row-1, col+1; i >= 0 && j < n; i, j = i-1, j+1 {
+		if chessboard[i][j] == "Q" {
+			return false
+		}
+	}
+	return true
+}
 ```
 ### Javascript 
 ```Javascript

problems/0063.不同路径II.md

@@ -272,40 +272,27 @@ func uniquePathsWithObstacles(obstacleGrid [][]int) int {
 	for i, _ := range dp {
 		dp[i] = make([]int, n)
 	}
-	// 初始化
+	// 初始化, 如果是障碍物, 后面的就都是0, 不用循环了
-	for i:=0;i<m;i++ {
+	for i := 0; i < m && obstacleGrid[i][0] == 0; i++ {
-		// 如果是障碍物, 后面的就都是0, 不用循环了
-		if obstacleGrid[i][0] == 1 {
-			break
-		}
 		dp[i][0] = 1
 	}
-	for i:=0;i<n;i++ {
+	for i := 0; i < n && obstacleGrid[0][i] == 0; i++ {
-		if obstacleGrid[0][i] == 1 {
-			break
-		}
 		dp[0][i] = 1
 	}
 	// dp数组推导过程
 	for i := 1; i < m; i++ {
 		for j := 1; j < n; j++ {
-			// 如果obstacleGrid[i][j]这个点是障碍物, 那么我们的dp[i][j]保持为0
+			// 如果obstacleGrid[i][j]这个点是障碍物, 那么dp[i][j]保持为0
 			if obstacleGrid[i][j] != 1 {
 				// 否则我们需要计算当前点可以到达的路径数
 				dp[i][j] = dp[i-1][j] + dp[i][j-1]
 			}
 		}
 	}
-	// debug遍历dp
-	//for i,_ := range dp {
-	//	for j,_ := range dp[i] {
-	//		fmt.Printf("%.2v,",dp[i][j])
-	//	}
-	//	fmt.Println()
-	//}
 	return dp[m-1][n-1]
 }
 
+
 ```
 
 Javascript

problems/0494.目标和.md

@@ -289,7 +289,7 @@ func findTargetSumWays(nums []int, target int) int {
 	for _, v := range nums {
 		sum += v
 	}
-	if target > sum {
+	if abs(target) > sum {
 		return 0
 	}
 	if (sum+target)%2 == 1 {
@@ -311,49 +311,12 @@ func findTargetSumWays(nums []int, target int) int {
 	}
 	return dp[bag]
 }
-```
-> 更新版，上一个跑不通了，因为会存在bag 小于0的情况
 
-```go
+func abs(x int) int {
-func findTargetSumWays(nums []int, target int) int {
+	return int(math.Abs(float64(x)))
-    //先转化为数学问题
-    //a-b=target
-    //a+b=sum
-    //a=(target+sum)/2
-    //求出sum
-    var sum int
-    for _,value:=range nums{
-        sum+=value
-    }
-    //如果sum<target或者 sum+target不是偶数（因为a是int） 或者两者之和小于0了
-    if sum<target||(sum+target)%2==1||(sum+target)<0{
-        return 0
-    }
-    //开始dp初始化
-    dp:=make([][]int,len(nums)+1)
-    for i:=0;i<=len(nums);i++{
-        tmp:=make([]int,(target+sum)/2+1)//背包容量
-        dp[i]=tmp
-    }
-    dp[0][0]=1//当背包容量为0，且物品为0时，填满背包就1种方法
-    for i:=0;i<len(nums)+1;i++{
-        if i==0{
-            continue
-        }
-        for j:=0;j<(target+sum)/2+1;j++{
-            if nums[i-1]<=j{//如果背包装的下
-                dp[i][j]=dp[i-1][j]+dp[i-1][j-nums[i-1]]
-            }else{
-                dp[i][j]=dp[i-1][j]
-            }
-        }
-    }
-    return dp[len(nums)][(target+sum)/2]
 }
 ```
 
-
-
 Javascript：
 ```javascript
 const findTargetSumWays = (nums, target) => {