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majelement.c
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185 lines (121 loc) · 3.24 KB
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#include <stdio.h>
#include <stdlib.h>
#define INDEX 0
#define MAJ 1
#define NOMAJ 0
void makeArr (int *nums, int end);
void printArray (int *nums, int end);
int mergeArray (int start, int end, int *nums);
/* main function for merging array. recursively called n / 2 */
void mergeSort (int start, int mid, int end, int *nums);
/*used to recursively divide main array /2 */
void divArray (int start, int end, int *nums, int *arrHalf);
/*function for copying lSide -> lArray & rSide -> rArray */
void reMerge (int *i, int *j, int *k, int lMax, int rMax, int *lSide, int *rSide, int *nums);
int findTurning (int *arrHalf, int target, int startPoint, int midPoint, int *turnPoint);
int main (void) {
int *nums;
int start, end, mid, target, turnPoint, majCheck;
start = INDEX;
scanf("%d", &end);
mid = end / 2;
nums = (int*) calloc(end, sizeof(int));
makeArr(nums, end);
// printArray(nums, end);
mergeArray(start, end - 1, nums);
// printArray(nums, end);
target = nums[mid];
findTurning(nums, target, start, mid, &turnPoint);
majCheck = turnPoint + mid;
// printf("Turn point is %d", turnPoint);
if (nums[turnPoint] == nums[majCheck]) {
printf("%d", MAJ);
}
else {
printf("%d", NOMAJ);
}
free(nums);
return 0;
}
void makeArr (int *nums, int end) {
int scan, i;
for (i = INDEX; i < end; i++) {
scanf("%d", &scan);
nums[i] = scan;
}
}
int mergeArray (int start, int end, int *nums) {
int mid;
if (start < end) {
mid = (start + end) / 2;
mergeArray(start, mid, nums);
mergeArray(mid + 1, end, nums);
mergeSort(start, mid, end, nums);
}
return 0;
}
void mergeSort (int start, int mid, int end, int *nums) {
int ltEnd, rtEnd, i, j, k;
i = INDEX;
j = INDEX;
k = start;
ltEnd = mid - start + 1;
rtEnd = end - mid;
int lSide[ltEnd], rSide[rtEnd];
divArray(start, ltEnd, nums, lSide);
divArray(mid + 1, rtEnd, nums, rSide);
reMerge(&i, &j, &k, ltEnd, rtEnd, lSide, rSide, nums);
}
void divArray (int start, int end, int *nums, int *arrHalf) {
int i;
for (i = INDEX; i < end; i++) {
arrHalf[i] = nums[i + start];
}
}
void reMerge (int *i, int *j, int *k, int lMax, int rMax, int *lSide, int *rSide, int *nums) {
while (*i < lMax && *j < rMax) {
if (lSide[*i] <= rSide[*j]) {
nums[*k] = lSide[*i];
*i = *i + 1;
}
else {
nums[*k] = rSide[*j];
*j = *j + 1;
}
*k = *k + 1;
/*k index of main array */
}
while (*i < lMax) {
nums[*k] = lSide[*i];
*i = *i + 1;
*k = *k + 1;
}
while (*j< rMax) {
nums[*k] = rSide[*j];
*j = *j + 1;
*k = *k + 1;
}
}
void printArray (int *nums, int end) {
int i;
for (i = INDEX; i < end; i++) {
printf(" %d ", nums[i]);
}
}
int findTurning (int *arrHalf, int target, int startPoint, int midPoint, int *turnPoint) {
int half;
if (arrHalf[midPoint] == target && arrHalf[midPoint - 1] < target) {
// printf("Inflection point found at co-ord %d", midPoint);
*turnPoint = midPoint;
return 1;
}
if (startPoint < midPoint) {
if (arrHalf[midPoint] < target && arrHalf[midPoint + 1] < target) {
findTurning(arrHalf, target, startPoint + 1, midPoint, turnPoint);
}
if (arrHalf[midPoint] == target && arrHalf[midPoint - 1] == target) {
findTurning(arrHalf, target, startPoint, midPoint - 1, turnPoint);
}
}
return 0;
}