Merge pull request neetcode-gh#2070 from Shyam-Makwana/0838-push-domi…

…noes.cpp

Create: 0838-push-dominoes.cpp

cpp/0838-push-dominoes.cpp

@@ -0,0 +1,39 @@
+/*
+ Time: O(n)
+ Space: O(n)
+*/
+
+class Solution {
+public:
+ string pushDominoes(string dominoes) {
+
+ string res = "";
+ char prev;
+ int n = dominoes.size(), count = 1;
+
+ vector<int> left(n, 0), right(n, 0);
+ for (int i = 0; i < n; i++) {
+ if (dominoes[i] == 'R') { count = 1; prev = 'R'; }
+ else if (dominoes[i] != '.') prev = dominoes[i];
+ if (prev == 'R' && dominoes[i] == '.') right[i] = count++;
+ }
+
+ prev = '.';
+ for (int i = n-1; i >= 0; i--) {
+ if (dominoes[i] == 'L') { count = 1; prev = 'L'; }
+ else if (dominoes[i] != '.') prev = dominoes[i];
+ if (prev == 'L' && dominoes[i] == '.') left[i] = count++;
+ }
+
+ for (int i = 0; i < n; i++) {
+ if (!left[i] && !right[i]) res += dominoes[i];
+ else if (!left[i]) res += 'R';
+ else if (!right[i]) res += 'L';
+ else if (left[i] == right[i]) res += '.';
+ else if (left[i] < right[i]) res += 'L';
+ else res += 'R';
+ }
+
+ return res;
+ }
+};