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Diffstat (limited to 'other/couples_holding_hands.cpp')
-rw-r--r-- | other/couples_holding_hands.cpp | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/other/couples_holding_hands.cpp b/other/couples_holding_hands.cpp new file mode 100644 index 0000000..7c3069a --- /dev/null +++ b/other/couples_holding_hands.cpp @@ -0,0 +1,38 @@ +// 765. Couples Holding Hands +#include "leetcode.h" + +/* + * there are 'n' couples sitting '2n' seats arranged in a row and want to hold + * hands. the people and seats are represented by an integer array 'row' where + * 'row[i]' is the id of the person sitting in the i'th seat. the couples are + * numbered in order, the first couple being '(0, 1)', the second couple being + * '(2, 3)', and so on with the last couple being '(2n -2, 2n -1)'. return the + * minimum number of swaps so that every couple is sitting side by side. a swap + * consists of choosing any two people then they stand up and switch seats. + */ + +class Solution { +public: + int minSwapsCouples(vector<int> &row) { + int ans = 0, n = row.size(); + vector<int> ptn(n, 0), pos(n, 0); + for (int i = 0; i < n; i++) { + ptn[i] = (!(i % 2) ? i + 1 : i - 1); + pos[row[i]] = i; + } + for (int i = 0; i < n; i++) + for (int j = ptn[pos[ptn[row[i]]]]; i != j; j = ptn[pos[ptn[row[i]]]]) { + swap(row[i], row[j]); + swap(pos[row[i]], pos[row[j]]); + ans++; + } + return ans; + } +}; + +int main() { + Solution obj; + vector<int> r1 = {0, 2, 1, 3}, r2 = {3, 2, 0, 1}; + printf("%d\n", obj.minSwapsCouples(r1)); // expect: 1 + printf("%d\n", obj.minSwapsCouples(r2)); // expect: 0 +} |