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Merge pull request #375 from 0xff-dev/931

Add solution and test-cases for problem 931

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Lines changed: 15 additions & 14 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,28 +1,29 @@`
`1`	`1`	`# [931.Minimum Falling Path Sum][title]`
`2`	`2`
`3`		`-> [!WARNING\|style:flat]`
`4`		`-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)`
`5`		`-`
`6`	`3`	`## Description`
	`4`	+Given an `n x n` array of integers `matrix`, return the minimum sum of any falling path through `matrix`.
	`5`	`+`
	`6`	+A falling path starts at any element in the first row and chooses the element in the next row that is either directly below or diagonally left/right. Specifically, the next element from position (`row, col`) will be (`row + 1, col - 1`), (`row + 1, col`), or (`row + 1, col + 1`).
	`7`	`+`
	`8`	`+Example 1:`
`7`	`9`
`8`		`-Example 1:`
	`10`	`+![example1](./failing1-grid.jpg)`
`9`	`11`
`10`	`12`	```
`11`		`-Input: a = "11", b = "1"`
`12`		`-Output: "100"`
	`13`	`+Input: matrix = [[2,1,3],[6,5,4],[7,8,9]]`
	`14`	`+Output: 13`
	`15`	`+Explanation: There are two falling paths with a minimum sum as shown.`
`13`	`16`	```
`14`	`17`
`15`		`-## 题意`
`16`		`-> ...`
	`18`	`+Example 2:`
`17`	`19`
`18`		`-## 题解`
	`20`	`+![example2](./failing2-grid.jpg)`
`19`	`21`
`20`		`-### 思路1`
`21`		`-> ...`
`22`		`-Minimum Falling Path Sum`
`23`		-```go
`24`	`22`	```
`25`		`-`
	`23`	`+Input: matrix = [[-19,57],[-40,-5]]`
	`24`	`+Output: -59`
	`25`	`+Explanation: The falling path with a minimum sum is shown.`
	`26`	+```
`26`	`27`
`27`	`28`	`## 结语`
`28`	`29`

Lines changed: 45 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,48 @@`
`1`	`1`	`package Solution`
`2`	`2`
`3`		`-func Solution(x bool) bool {`
`4`		`- return x`
	`3`	`+func Solution(matrix [][]int) int {`
	`4`	`+ rows, cols := len(matrix), len(matrix[0])`
	`5`	`+ dp := make([][]int, 2)`
	`6`	`+ dp[0], dp[1] = make([]int, cols), make([]int, cols)`
	`7`	`+ visited := make([]bool, cols)`
	`8`	`+ loop := 1`
	`9`	`+ for col := 0; col < cols; col++ {`
	`10`	`+ dp[0][col] = matrix[0][col]`
	`11`	`+ }`
	`12`	`+`
	`13`	`+ for row := 1; row < rows; row++ {`
	`14`	`+ for col := 0; col < cols; col++ {`
	`15`	`+ down := dp[1-loop][col] + matrix[row][col]`
	`16`	`+ if !visited[col] \|\| dp[loop][col] > down {`
	`17`	`+ dp[loop][col] = down`
	`18`	`+ visited[col] = true`
	`19`	`+ }`
	`20`	`+ if col < cols-1 {`
	`21`	`+ downRight := dp[1-loop][col] + matrix[row][col+1]`
	`22`	`+ if !visited[col+1] \|\| dp[loop][col+1] > downRight {`
	`23`	`+ dp[loop][col+1] = downRight`
	`24`	`+ visited[col+1] = true`
	`25`	`+ }`
	`26`	`+ }`
	`27`	`+ if col > 0 {`
	`28`	`+ downLeft := dp[1-loop][col] + matrix[row][col-1]`
	`29`	`+ if !visited[col-1] \|\| dp[loop][col-1] > downLeft {`
	`30`	`+ dp[loop][col-1] = downLeft`
	`31`	`+ visited[col-1] = true`
	`32`	`+ }`
	`33`	`+ }`
	`34`	`+ }`
	`35`	`+`
	`36`	`+ for col := 0; col < cols; col++ {`
	`37`	`+ visited[col] = false`
	`38`	`+ }`
	`39`	`+ loop = 1 - loop`
	`40`	`+ }`
	`41`	`+ ans := dp[1-loop][0]`
	`42`	`+ for i := 1; i < cols; i++ {`
	`43`	`+ if dp[1-loop][i] < ans {`
	`44`	`+ ans = dp[1-loop][i]`
	`45`	`+ }`
	`46`	`+ }`
	`47`	`+ return ans`
`5`	`48`	`}`

Lines changed: 13 additions & 7 deletions

Original file line number	Diff line number	Diff line change
`@@ -10,12 +10,18 @@ func TestSolution(t *testing.T) {`
`10`	`10`	`// 测试用例`
`11`	`11`	`cases := []struct {`
`12`	`12`	`name string`
`13`		`- inputs bool`
`14`		`- expect bool`
	`13`	`+ inputs [][]int`
	`14`	`+ expect int`
`15`	`15`	`}{`
`16`		`- {"TestCase", true, true},`
`17`		`- {"TestCase", true, true},`
`18`		`- {"TestCase", false, false},`
	`16`	`+ {"TestCase1", [][]int{`
	`17`	`+ {2, 1, 3},`
	`18`	`+ {6, 5, 4},`
	`19`	`+ {7, 8, 9},`
	`20`	`+ }, 13},`
	`21`	`+ {"TestCase2", [][]int{`
	`22`	`+ {-19, 57},`
	`23`	`+ {-40, -5},`
	`24`	`+ }, -59},`
`19`	`25`	`}`
`20`	`26`
`21`	`27`	`// 开始测试`
`@@ -30,10 +36,10 @@ func TestSolution(t *testing.T) {`
`30`	`36`	`}`
`31`	`37`	`}`
`32`	`38`
`33`		`-//压力测试`
	`39`	`+//压力测试`
`34`	`40`	`func BenchmarkSolution(b *testing.B) {`
`35`	`41`	`}`
`36`	`42`
`37`		`-//使用案列`
	`43`	`+//使用案列`
`38`	`44`	`func ExampleSolution() {`
`39`	`45`	`}`

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