richie-rich

richie-rich.cpp

@@ -0,0 +1,101 @@
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <limits.h>
+#include <stdbool.h>
+
+char* richieRich(char* s, int n, int k){
+    if(n==1) {
+        if(k>=1)
+            return "9";
+        else return s;
+    }
+    int a,b;
+    if(n%2==0) {
+        b=n/2;
+        a=b-1;
+    } else {
+        b=n/2+1;
+        a=b-2;
+        if(k==1 && s[b-1] < '9'){
+            s[b-1] = '9';
+            k--;
+        }
+    }
+    int change[512000], x=0;
+    for(; b<n && a>=0; b++, a--) {
+        if(s[a]==s[b])
+            continue;
+        if(k<=0)
+            break;
+        if(s[a]>s[b]) {
+            s[b]=s[a];
+            change[x++]=a;
+            k--;
+        } else {
+            s[a]=s[b];
+            change[x++]=a;
+            k--;
+        }
+    }
+    x=x-1;
+    if(b!=n)
+        return "-1";
+    int y=0;
+    int w=x;
+    while(k>1 && (n-y-1)>=y) {
+        w=x;
+        if(s[y]!='9') {
+            s[y]=s[n-y-1]='9';
+            if(y == n-y-1){
+                while(w>=0 ){
+                    if( change[w]==y) {
+                        //k=k-1;
+                        break;
+                    } 
+                    w--;
+                }
+                if(w<0)  k=k-1;
+
+            }
+            else {
+                while(w>=0 ){
+                    if(change[w]==y) {
+                        k=k-1;
+                        break;    
+                    } 
+                    w--;
+                }
+                if(w <0 )
+                     k=k-2;
+            }
+        }
+        y++;
+    }
+    while(k==1 && x>=0) {
+        if(s[change[x]]!='9') {
+            s[change[x]]='9';
+            s[n-change[x]-1]='9';
+            k--;
+        }
+        x--;
+    }
+    if(k>=1 && n%2!=0)
+        s[n/2]='9';
+    return s;
+}
+
+int main() {
+    int n; 
+    scanf("%i", &n);
+    int k; 
+    scanf("%i", &k);
+    char* s = (char *)malloc(512000 * sizeof(char));
+    scanf("%s", s);
+    int result_size;
+    char* result = richieRich(s, n, k);
+    printf("%s\n", result);
+    return 0;
+}