E - Replace With the Previous, Minimize

https://codeforces.com/contest/1675/submission/155988940

Codeforces/1675/E/E.cpp

@@ -0,0 +1,54 @@
+#include <iostream>
+#include <string>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2e5 + 5;
+
+int t, n, k, max, a[30];
+std::string s;
+
+signed main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> t;
+
+    while (t--) {
+        max = 0;
+        for (int i = 0; i < 26; i++) {
+            a[i] = i;
+        }
+
+        cin >> n >> k >> s;
+
+        for (int i = 0; i < s.size(); i++) {
+            int x = s[i] - 'a';
+
+            if (x > k) {
+                int t = x - (k - max);
+
+                for (int j = x; j >= t; j--) {
+                    a[j] = t;
+                }
+
+                break;
+            }
+
+            for (int j = x; ~j; j--) {
+                a[j] = 0;
+            }
+
+            max = std::max(max, x);
+        }
+
+        for (int i = 0; i < s.size(); i++) {
+            cout << char(a[s[i] - 'a'] + 'a');
+        }
+
+        cout << endl;
+    }
+
+    return 0;
+}