git reimport

archive/2016.08/2016.08.01 - unsorted/Sazanka0G.java

@@ -0,0 +1,67 @@
+package chelper;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+import io.InputReader;
+import io.OutputWriter;
+
+public class Sazanka0G {
+  int[] powers = new int[10];
+
+  public void solve(int testNumber, InputReader in, OutputWriter out) {
+    int k = 6;
+
+    for (int i = 0; i < 10; i++) {
+      powers[i] = (int) Math.pow(i, k);
+    }
+
+    int[] dp = new int[10000000];
+    Arrays.fill(dp, -1);
+
+    long sum = 0;
+    for (int i = 1; i <= 1000000; i++) {
+      sum += f(i, dp);
+    }
+    out.println(sum);
+  }
+
+  int nextHappy(int n) {
+    int x = n;
+    int ans = 0;
+    while (x > 0) {
+      int t = x % 10;
+      x /= 10;
+      ans += powers[t];
+    }
+    return ans;
+  }
+
+  int f(int x, int[] dp) {
+    if (dp[x] == -1) {
+      int t = nextHappy(x);
+      dp[x] = -2;
+      dp[x] = Math.min(x, f(t, dp));
+    }
+    if (dp[x] == -2) { // found loop
+      Set<Integer> loop = new HashSet<>();
+      int t = x;
+      while (true) {
+        loop.add(t);
+        t = nextHappy(t);
+        if (t == x) {
+          break;
+        }
+      }
+      int min = Integer.MAX_VALUE;
+      for (int i : loop) {
+        min = Math.min(min, i);
+      }
+      for (int i : loop) {
+        dp[i] = min;
+      }
+    }
+    return dp[x];
+  }
+}