Hdu5014number sequence (Greedy)

Hdu5014number sequence (Greedy)

Question Link

Question:
N is given, and a number string is given. The length is n + 1 and the range is [0, n-1]. then ask you to find another sequence B to meet the above requirements, and make T = A0 ^ b0 + AI + 1 ^ Bi + 1 +... + an ^ BN is the largest.

Solution:
If a number is exclusive or requires the maximum result, it is best to take the binary complementary number of this number, it can be found that each time a number is found and the corresponding complementary number is a range. In this way, we can find the best matching point for each point in a certain interval.

Code:

#include <cstdio>#include <cstring>typedef long long ll;const int N = 1e5 + 5;const int M = 20;int num[N];int Map[N];int n;ll t[M];void init () {    t[0] = 1;    for (int i = 1; i <= M; i++)        t[i] = t[i - 1] * 2;}int main () {    init();    while (scanf ("%d", &n) == 1) {        for (int i = 0; i <= n; i++)            scanf ("%d", &num[i]);        int rear = n;        int front;        ll ans = 0;//        printf ("%lld\n", t[M - 1]);        while (rear >= 0) {            for (int i = 0; i < M; i++)                if (t[i] > rear) {                    front = t[i] - rear - 1;                    break;                        }            for (int i = 0; i < (rear - front + 1) / 2; i++) {                Map[rear - i] = front + i;                Map[front + i] = rear - i;            }            if (rear == front)                Map[rear] = front;            rear = front - 1;        }        for (int i = 0; i <= n; i++)            ans += num[i] ^ Map[num[i]];        printf ("%lld\n", ans);        for (int i = 0; i < n; i++)            printf("%d ", Map[num[i]]);        printf ("%d\n", Map[num[n]]);    }    return 0;}

Hdu5014number sequence (Greedy)