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// 1007. Minimum Domino Rotations For Equal Row
#include "leetcode.h"
/*
* in a row of dominoes, 'tops[i]' and 'bottoms[i]' represents the top and
* bottom halves of the i'th domino. we may rotate the i'th domino so that
* 'tops[i]' and 'bottoms[i]' swap values. return the minimum number of
* rotations so that all values in 'tops' are the same, or all values in
* 'bottoms' are the same. if it cannot be done, return -1.
*/
int minDominoRotations(int *tops, int topsSize, int *bottoms, int bottomsSize) {
int mask = 0x7E, num = -1, a = 0, b = 0;
for (int i = 0; i < topsSize; i++) {
mask &= ((1 << tops[i]) | (1 << bottoms[i]));
if (!mask)
return -1;
}
while (mask) {
num++;
mask >>= 1;
}
for (int i = 0; i < topsSize; i++) {
if (tops[i] == num)
a++;
if (bottoms[i] == num)
b++;
}
int max = a > b ? a : b;
return topsSize - max;
}
int main() {
int t1[] = {2, 1, 2, 4, 2, 2}, b1[] = {5, 2, 6, 2, 3, 2};
int t2[] = {3, 5, 1, 2, 3}, b2[] = {3, 6, 3, 3, 4};
printf("%d\n", minDominoRotations(t1, ARRAY_SIZE(t1), b1,
ARRAY_SIZE(b1))); // expect: 2
printf("%d\n", minDominoRotations(t2, ARRAY_SIZE(t2), b2,
ARRAY_SIZE(b2))); // expect: -1
}
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