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307-Range Sum Query - Mutable.c
83 lines (74 loc) · 2.38 KB
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307-Range Sum Query - Mutable.c
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typedef struct SegmentTreeNode {
int start, end, sum;
struct SegmentTreeNode *left, *right;
} SegTreeNode;
SegTreeNode* initTree(int* nums, int start, int end) {
if (start > end) {
return NULL;
}
SegTreeNode* node = malloc(sizeof(SegTreeNode));
node->start = start;
node->end = end;
if (start == end) {
node->sum = nums[start];
} else {
int mid = start + (end - start) / 2;
node->left = initTree(nums, start, mid);
node->right = initTree(nums, mid + 1, end);
node->sum = node->left->sum + node->right->sum;
}
return node;
}
void updateTree(SegTreeNode* root, int i, int val) {
if (root->start == root->end) {
root->sum = val;
} else {
int mid = root->start + (root->end - root->start) / 2;
if (i <= mid) {
updateTree(root->left, i, val);
} else {
updateTree(root->right, i, val);
}
root->sum = root->left->sum + root->right->sum;
}
}
int sumTree(SegTreeNode* root, int start, int end) {
if (root->start == start && root->end == end) {
return root->sum;
} else {
int mid = root->start + (root->end - root->start) / 2;
if (end <= mid) {
return sumTree(root->left, start, end);
} else if (start > mid) {
return sumTree(root->right, start, end);
} else {
return sumTree(root->left, start, mid) + sumTree(root->right, mid+1, end);
}
}
}
struct NumArray {
SegTreeNode* root;
};
/** Initialize your data structure here. */
struct NumArray* NumArrayCreate(int* nums, int numsSize) {
struct NumArray* numArr = malloc(sizeof(struct NumArray));
numArr->root = initTree(nums, 0, numsSize-1);
return numArr;
}
void update(struct NumArray* numArray, int i, int val) {
updateTree(numArray->root, i, val);
}
int sumRange(struct NumArray* numArray, int i, int j) {
return sumTree(numArray->root, i, j);
}
/** Deallocates memory previously allocated for the data structure. */
void NumArrayFree(struct NumArray* numArray) {
//free(numArray->nums);
//free(numArray->sums);
}
// Your NumArray object will be instantiated and called as such:
// struct NumArray* numArray = NumArrayCreate(nums, numsSize);
// sumRange(numArray, 0, 1);
// update(numArray, 1, 10);
// sumRange(numArray, 1, 2);
// NumArrayFree(numArray);