真的骚的一个题，看了半天只会个前缀和+暴力。。
纯考思维。。
#include#include #include #define M 41#define N 100011#define max(x, y) ((x) > (y) ? (x) : (y))int n, m, ans, last;struct node{ int sum[M], id; node() { id = 0; memset(sum, 0, sizeof(sum)); }}p[N];inline bool cmp(node x, node y){ int i; for(i = 1; i <= m; i++) if(x.sum[i] != y.sum[i]) return x.sum[i] < y.sum[i]; return x.id < y.id;}inline bool check(int x, int y){ int i; for(i = 1; i <= m; i++) if(p[x].sum[i] != p[y].sum[i]) return 0; return 1;}int main(){ int i, j, x; scanf("%d %d", &n, &m); for(i = 1; i <= n; i++) { scanf("%d", &x); p[i].id = i; for(j = 1; j <= m; j++) p[i].sum[j] = p[i - 1].sum[j] + bool(x & (1 << j - 1)); } for(i = 1; i <= n; i++) for(j = 1; j <= m; j++) p[i].sum[j] -= p[i].sum[m]; std::sort(p + 1, p + n + 2, cmp); last = p[1].id; for(i = 2; i <= n + 1; i++) { if(check(i, i - 1)) ans = max(ans, p[i].id - last); else last = p[i].id; } printf("%d\n", ans); return 0;}