Codeforces 1028E Restore Array 构造
我发现我构造题真的不会写, 想了好久才想出来。。
我们先把n = 2, 所有数字相等, 所有数字等于0的都特判掉。
找到一个b[ i ] > b[ i - 1 ]的位置把它移到最后一个位置, 并且使其a[ i ] = b[ i ]然后从后往前构造。
#include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk make_pair #define PLL pair<LL, LL> #define PLI pair<LL, int> #define PII pair<int, int> #define SZ(x) ((int)x.size()) #define ull unsigned long long using namespace std; const int N = 1e6 + 7; const int inf = 0x3f3f3f3f; const LL INF = 0x3f3f3f3f3f3f3f3f; const int mod = 1e9 + 7; const double eps = 1e-8; const double PI = acos(-1); int n, who = -1, id[N]; LL a[N], b[N]; bool flag; int main() { scanf("%d", &n); for(int i = 0; i < n; i++) { scanf("%lld", &b[i]); flag |= b[i]; } for(int i = 0; i < n; i++) { if(b[(i-1+n)%n] < b[i]) who = i; } if(!flag) { puts("YES"); for(int i = 0; i < n; i++) printf("1 "); puts(""); } else if(n == 2) { if(a[0] == a[1]) puts("NO"); else { puts("YES"); if(a[0] > a[1]) printf("%lld %lld\n", a[0], a[0] + a[1]); else printf("%lld %lld\n", a[0] + a[1], a[1]); } } else { if(who == -1) return puts("NO"), 0; int now = 0, cur = (who + 1) % n; for(int i = 1; i <= n; i++) { id[now++] = cur; cur = (cur + 1) % n; } a[id[n - 1]] = b[id[n - 1]]; for(int i = n - 2; i >= 0; i--) { LL low = b[id[(i - 1 + n) % n]] + 1; LL mo = a[id[i + 1]]; a[id[i]] = low + (((b[id[i]] % mo) - (low % mo)) % mo + mo) % mo; } puts("YES"); for(int i = 0; i < n; i++) printf("%lld ", a[i]); puts(""); } return 0; } /* */