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[LEET-523] add 523

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+55

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leetcode-algorithms/src
- main/java/com/stevesun/solutions
  - ContinuousSubarraySum.java
- test/java/com/stevesun
  - ContinuousSubarraySumTest.java

+55

-9

lines changed

Lines changed: 10 additions & 9 deletions

Original file line number	Diff line number	Diff line change
`@@ -1,7 +1,9 @@`
`1`	`1`	`packagecom.stevesun.solutions;`
`2`	`2`
`3`	`3`	`/**`
`4`		`- * Given a list of non-negative numbers and a target integer k, write a function to check if the array has a continuous subarray of size at least 2 that sums up to the multiple of k, that is, sums up to n*k where n is also an integer.`
	`4`	`+ * Given a list of non-negative numbers and a target integer k,`
	`5`	`+ * write a function to check if the array has a continuous subarray of size at least 2`
	`6`	`+ * that sums up to the multiple of k, that is, sums up to n*k where n is also an integer.`
`5`	`7`
`6`	`8`	`Example 1:`
`7`	`9`	`Input: [23, 2, 4, 6, 7], k=6`
`@@ -30,17 +32,16 @@ public boolean checkSubarraySum(int[] nums, int k) {`
`30`	`32`	`}`
`31`	`33`
`32`	`34`	`//then k cannot be zero any more`
`33`		`-if (k ==0)returnfalse;`
	`35`	`+if (k ==0 \|\|nums.length <2)returnfalse;`
`34`	`36`
`35`		`-int[]preSums =newint[nums.length];`
`36`		`-preSums[0] =nums[0];`
`37`		`-for (inti =1;i <nums.length;i++) {`
`38`		`-preSums[i] =preSums[i-1] +nums[i];`
	`37`	`+int[]preSums =newint[nums.length+1];`
	`38`	`+for (inti =1;i <=nums.length;i++) {`
	`39`	`+preSums[i] =preSums[i-1] +nums[i-1];`
`39`	`40`	`}`
`40`	`41`
`41`		`-for (inti =1;i <nums.length;i++) {`
`42`		`-for (intj =0;j <=i-1;j++) {`
`43`		`-if ((preSums[i] -nums[j]) %k ==0)returntrue;`
	`42`	`+for (inti =1;i <=nums.length;i++) {`
	`43`	`+for (intj =0;j <i-1;j++) {`
	`44`	`+if ((preSums[i] -preSums[j]) %k ==0)returntrue;`
`44`	`45`	`}`
`45`	`46`	`}`
`46`	`47`	`returnfalse;`

Lines changed: 45 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -67,4 +67,49 @@ public void test5(){`
`67`	`67`	`assertEquals(expected,actual);`
`68`	`68`	`}`
`69`	`69`
	`70`	`+@Test`
	`71`	`+publicvoidtest6(){`
	`72`	`+nums =newint[]{1,1};`
	`73`	`+expected =true;`
	`74`	`+k =2;`
	`75`	`+actual =test.checkSubarraySum(nums,k);`
	`76`	`+assertEquals(expected,actual);`
	`77`	`+ }`
	`78`	`+`
	`79`	`+@Test`
	`80`	`+publicvoidtest7(){`
	`81`	`+nums =newint[]{0};`
	`82`	`+expected =false;`
	`83`	`+k = -1;`
	`84`	`+actual =test.checkSubarraySum(nums,k);`
	`85`	`+assertEquals(expected,actual);`
	`86`	`+ }`
	`87`	`+`
	`88`	`+@Test`
	`89`	`+publicvoidtest8(){`
	`90`	`+nums =newint[]{23,2,4,6,7};`
	`91`	`+expected =true;`
	`92`	`+k = -6;`
	`93`	`+actual =test.checkSubarraySum(nums,k);`
	`94`	`+assertEquals(expected,actual);`
	`95`	`+ }`
	`96`	`+`
	`97`	`+@Test`
	`98`	`+publicvoidtest9(){`
	`99`	`+nums =newint[]{1,2,3};`
	`100`	`+expected =false;`
	`101`	`+k =4;`
	`102`	`+actual =test.checkSubarraySum(nums,k);`
	`103`	`+assertEquals(expected,actual);`
	`104`	`+ }`
	`105`	`+`
	`106`	`+@Test`
	`107`	`+publicvoidtest10(){`
	`108`	`+nums =newint[]{5,2,4};`
	`109`	`+expected =false;`
	`110`	`+k =5;`
	`111`	`+actual =test.checkSubarraySum(nums,k);`
	`112`	`+assertEquals(expected,actual);`
	`113`	`+ }`
	`114`	`+`
`70`	`115`	`}`

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