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add: Arithmetic Slices

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`@@ -55,6 +55,7 @@ This is the solutions collection of my LeetCode submissions, most of them are pr`
`55`	`55`	`\|371\|[Sum of Two Integers](https://leetcode.com/problems/sum-of-two-integers/)\|[JavaScript](./src/sum-of-two-integers/res.js)\|Easy\|`
`56`	`56`	`\|384\|[Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/)\|[JavaScript](./src/shuffle-an-array/res.js)\|Medium\|`
`57`	`57`	`\|404\|[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/)\|[JavaScript](./src/sum-of-left-leaves/res.js)\|Easy\|`
	`58`	`+\|413\|[Arithmetic Slices](https://leetcode.com/problems/arithmetic-slices/)\|[JavaScript](./src/arithmetic-slices/res.js)\|Medium\|`
`58`	`59`	`\|416\|[Partition Equal Subset Sum](https://leetcode.com/problems/partition-equal-subset-sum/)\|[JavaScript](./src/partition-equal-subset-sum/res.js)\|Medium\|`
`59`	`60`	`\|434\|[Number of Segments in a String](https://leetcode.com/problems/number-of-segments-in-a-string/)\|[JavaScript](./src/number-of-segments-in-a-string/res.js)\|Easy\|`
`60`	`61`	`\|494\|[Target Sum](https://leetcode.com/problems/target-sum/)\|[JavaScript](./src/target-sum/res.js)\|Medium\|`

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	`1`	`+/**`
	`2`	`+ * res.js`
	`3`	`+ *@authors Joe Jiang (hijiangtao@gmail.com)`
	`4`	`+ *@date 2017-04-13 11:02:22`
	`5`	`+ *`
	`6`	`+ * A zero-indexed array A consisting of N numbers is given. A slice of that array is any pair of integers (P, Q) such that 0 <= P < Q < N.`
	`7`	`+ * A slice (P, Q) of array A is called arithmetic if the sequence:`
	`8`	`+ * A[P], A[P + 1], ..., A[Q - 1], A[Q] is arithmetic. In particular, this means that P + 1 < Q.`
	`9`	`+ * The function should return the number of arithmetic slices in the array A.`
	`10`	`+ *`
	`11`	`+ *@param {number[]} A`
	`12`	`+ *@return {number}`
	`13`	`+ */`
	`14`	`+letnumberOfArithmeticSlices=function(A){`
	`15`	`+letlen=A.length;`
	`16`	`+if(len<3){`
	`17`	`+return0;`
	`18`	`+}`
	`19`	`+`
	`20`	`+letres=0,`
	`21`	`+interval=[];`
	`22`	`+`
	`23`	`+// 构建元素差数组`
	`24`	`+for(leti=1;i<len;i++){`
	`25`	`+interval.push(A[i]-A[i-1]);`
	`26`	`+}`
	`27`	`+`
	`28`	`+letcount=2,`
	`29`	`+difPre=interval[0];`
	`30`	`+`
	`31`	`+len--;`
	`32`	`+for(leti=1;i<len;i++){`
	`33`	`+letdifNow=interval[i];`
	`34`	`+`
	`35`	`+if(difNow===difPre){`
	`36`	`+count++;`
	`37`	`+}else{`
	`38`	`+res+=Sum(count);// 计算当前积攒元素个数下的 arithmetic 个数`
	`39`	`+difPre=difNow;`
	`40`	`+count=2;`
	`41`	`+}`
	`42`	`+}`
	`43`	`+`
	`44`	`+if(count>2){`
	`45`	`+res+=Sum(count);`
	`46`	`+}`
	`47`	`+`
	`48`	`+returnres;`
	`49`	`+};`
	`50`	`+`
	`51`	`+letSum=function(n){`
	`52`	`+// console.log(n);`
	`53`	`+return(n-2)*(n-1)/2;`
	`54`	`+};`

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