leetcode/FindSum.java at master · actor168/leetcode · GitHub

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classNumArray {

privateint[] arr;

publicNumArray(int[] nums) {
arr = newint[nums.length];
arr[0] = nums[0];
for (inti = 1; i < nums.length; i++){
arr[i] = arr[i-1] + nums[i];
 }
 }

publicintsumRange(inti, intj) {
intleft = 0;
if (j < 0) {
return0;
 }
if ( i < 1) {
left = 0;
 } else {
left = arr[i-1];
 }
returnarr[j] - left;
 }

publicvoidprint() {
for (inti = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
 }
System.out.println();
 }
}


publicclassFindSum{
publicstaticvoidmain(String[] args) {
int[] nums = {-2, 0, 3, -5, 2, -1};

NumArrayobj = newNumArray(nums);

obj.print();

System.out.println(obj.sumRange(0,2));
System.out.println(obj.sumRange(0,5));
System.out.println(obj.sumRange(2,5));
System.out.println(obj.sumRange(0,0));
System.out.println(obj.sumRange(2,2));
System.out.println(obj.sumRange(2,3));
System.out.println(obj.sumRange(0,-1));
 }
}