add c/0303-range-sum-query-immutable.c

c/0303-range-sum-query-immutable.c

@@ -0,0 +1,42 @@
+typedef struct {
+ int size;
+ int *sums;
+} NumArray;
+
+
+NumArray* numArrayCreate(int* nums, int numsSize) {
+ NumArray *n = (NumArray*)malloc(sizeof(NumArray));
+ n->size = numsSize;
+ n->sums = (int*)malloc(sizeof(int) * numsSize);
+
+ // Pre calculate the sum of each index from 0.
+ n->sums[0] = nums[0];
+ for(int i = 1; i < numsSize; i++){
+ n->sums[i] = n->sums[i-1] + nums[i];
+ }
+
+ return n;
+}
+
+int numArraySumRange(NumArray* obj, int left, int right) {
+ assert(obj);
+ if (left == 0) {
+ return obj->sums[right];
+ }
+ return obj->sums[right] - obj->sums[left - 1];
+}
+
+void numArrayFree(NumArray* obj) {
+ if (obj) {
+ free(obj->sums);
+ free(obj);
+ }
+}
+
+/**
+ * Your NumArray struct will be instantiated and called as such:
+ * NumArray* obj = numArrayCreate(nums, numsSize);
+ * int param_1 = numArraySumRange(obj, left, right);
+
+ * numArrayFree(obj);
+*/