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Merge pull request youngyangyang04#2727 from markwang1992/494-findTargetSumWays

494.目标和增加Go二维dp解法

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`@@ -706,6 +706,57 @@ class Solution:`
`706`	`706`	```
`707`	`707`
`708`	`708`	`### Go`
	`709`	`+二维dp`
	`710`	+```go
	`711`	`+func findTargetSumWays(nums []int, target int) int {`
	`712`	`+ sum := 0`
	`713`	`+ for _, v := range nums {`
	`714`	`+ sum += v`
	`715`	`+ }`
	`716`	`+ if math.Abs(float64(target)) > float64(sum) {`
	`717`	`+ return 0 // 此时没有方案`
	`718`	`+ }`
	`719`	`+ if (target + sum) % 2 == 1 {`
	`720`	`+ return 0 // 此时没有方案`
	`721`	`+ }`
	`722`	`+ bagSize := (target + sum) / 2`
	`723`	`+`
	`724`	`+ dp := make([][]int, len(nums))`
	`725`	`+ for i := range dp {`
	`726`	`+ dp[i] = make([]int, bagSize + 1)`
	`727`	`+ }`
	`728`	`+`
	`729`	`+ // 初始化最上行`
	`730`	`+ if nums[0] <= bagSize {`
	`731`	`+ dp[0][nums[0]] = 1`
	`732`	`+ }`
	`733`	`+`
	`734`	`+ // 初始化最左列,最左列其他数值在递推公式中就完成了赋值`
	`735`	`+ dp[0][0] = 1`
	`736`	`+`
	`737`	`+ var numZero float64`
	`738`	`+ for i := range nums {`
	`739`	`+ if nums[i] == 0 {`
	`740`	`+ numZero++`
	`741`	`+ }`
	`742`	`+ dp[i][0] = int(math.Pow(2, numZero))`
	`743`	`+ }`
	`744`	`+`
	`745`	`+ // 以下遍历顺序行列可以颠倒`
	`746`	`+ for i := 1; i < len(nums); i++ { // 行,遍历物品`
	`747`	`+ for j := 0; j <= bagSize; j++ { // 列,遍历背包`
	`748`	`+ if nums[i] > j {`
	`749`	`+ dp[i][j] = dp[i-1][j]`
	`750`	`+ } else {`
	`751`	`+ dp[i][j] = dp[i-1][j] + dp[i-1][j-nums[i]]`
	`752`	`+ }`
	`753`	`+ }`
	`754`	`+ }`
	`755`	`+ return dp[len(nums)-1][bagSize]`
	`756`	`+}`
	`757`	+```
	`758`	`+`
	`759`	`+一维dp`
`709`	`760`	```go
`710`	`761`	`func findTargetSumWays(nums []int, target int) int {`
`711`	`762`	`sum := 0`

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