init

greed/316.h

@@ -0,0 +1,31 @@
+#include <string.h>
+#include <stdlib.h>
+char* removeDuplicateLetters(char* s) {
+    int vis[26], num[26];
+    memset(vis, 0, sizeof(vis));
+    memset(num, 0, sizeof(num));
+
+    int n = strlen(s);
+    for (int i = 0; i < n; i++) {
+        num[s[i] - 'a']++;
+    }
+
+    char* stk = (char*)malloc(sizeof(char) * 27);
+    int stkTop = 0;
+    for (int i = 0; i < n; i++) {
+        if (!vis[s[i] - 'a']) {
+            while (stkTop > 0 && stk[stkTop - 1] > s[i]) {
+                if (num[stk[stkTop - 1] - 'a'] > 0) {
+                    vis[stk[--stkTop] - 'a'] = 0;
+                } else {
+                    break;
+                }
+            }
+            vis[s[i] - 'a'] = 1;
+            stk[stkTop++] = s[i];
+        }
+        num[s[i] - 'a'] -= 1;
+    }
+    stk[stkTop] = '\0';
+    return stk;
+}