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markwang1992 markwang1992

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494.目标和增加Go二维dp解法

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`‎problems/0494.目标和.md`

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`@@ -675,6 +675,57 @@ class Solution:`
`675`	`675`	```
`676`	`676`
`677`	`677`	`### Go`
	`678`	`+二维dp`
	`679`	+```go
	`680`	`+func findTargetSumWays(nums []int, target int) int {`
	`681`	`+ sum := 0`
	`682`	`+ for _, v := range nums {`
	`683`	`+ sum += v`
	`684`	`+ }`
	`685`	`+ if math.Abs(float64(target)) > float64(sum) {`
	`686`	`+ return 0 // 此时没有方案`
	`687`	`+ }`
	`688`	`+ if (target + sum) % 2 == 1 {`
	`689`	`+ return 0 // 此时没有方案`
	`690`	`+ }`
	`691`	`+ bagSize := (target + sum) / 2`
	`692`	`+`
	`693`	`+ dp := make([][]int, len(nums))`
	`694`	`+ for i := range dp {`
	`695`	`+ dp[i] = make([]int, bagSize + 1)`
	`696`	`+ }`
	`697`	`+`
	`698`	`+ // 初始化最上行`
	`699`	`+ if nums[0] <= bagSize {`
	`700`	`+ dp[0][nums[0]] = 1`
	`701`	`+ }`
	`702`	`+`
	`703`	`+ // 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`
	`704`	`+ dp[0][0] = 1`
	`705`	`+`
	`706`	`+ var numZero float64`
	`707`	`+ for i := range nums {`
	`708`	`+ if nums[i] == 0 {`
	`709`	`+ numZero++`
	`710`	`+ }`
	`711`	`+ dp[i][0] = int(math.Pow(2, numZero))`
	`712`	`+ }`
	`713`	`+`
	`714`	`+ // 以下遍历顺序行列可以颠倒`
	`715`	`+ for i := 1; i < len(nums); i++ { // 行,遍历物品`
	`716`	`+ for j := 0; j <= bagSize; j++ { // 列,遍历背包`
	`717`	`+ if nums[i] > j {`
	`718`	`+ dp[i][j] = dp[i-1][j]`
	`719`	`+ } else {`
	`720`	`+ dp[i][j] = dp[i-1][j] + dp[i-1][j-nums[i]]`
	`721`	`+ }`
	`722`	`+ }`
	`723`	`+ }`
	`724`	`+ return dp[len(nums)-1][bagSize]`
	`725`	`+}`
	`726`	+```
	`727`	`+`
	`728`	`+一维dp`
`678`	`729`	```go
`679`	`730`	`func findTargetSumWays(nums []int, target int) int {`
`680`	`731`	`sum := 0`

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