cf1102F. Elongated Matrix(状压dp)

#include<bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 10, INF = 1e9 + 10, SS = 18;
template <typename A, typename B> inline bool chmin(A &a, B b){if(a > b) {a = b; return 1;} return 0;}
template <typename A, typename B> inline bool chmax(A &a, B b){if(a < b) {a = b; return 1;} return 0;}
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
    return x * f;
}
int N, M, Lim, a[SS][MAXN], f[1 << (SS)][SS], Mn[SS][MAXN], L[SS][MAXN];
void Pre() {
    for(int i = 1; i <= N; i++) {
        for(int j = 1; j <= N; j++) {
            Mn[i][j] = INF; L[i][j] = INF;
            for(int k = 1; k <= M; k++) chmin(Mn[i][j], (i == j) ? a[i][k] : abs(a[i][k] - a[j][k]));
            for(int k = 1; k < M; k++) chmin(L[i][j], abs(a[i][k] - a[j][k + 1]));
        }
    }
}
int DP(int bg) {
    memset(f, -1, sizeof(f));
    f[1 << (bg - 1)][bg] = INF;
    for(int sta = 0; sta < Lim; sta++) {
        for(int i = 1; i <= N; i++) {
            if(f[sta][i] == -1) continue;
            for(int j = 1; j <= N; j++) {
                if(sta & (1 << (j - 1))) continue;
                chmax(f[sta | (1 << (j - 1))][j], min(f[sta][i], Mn[i][j]));
            }
        }
    }
    int now = 0;
    for(int i = 1; i <= N; i++) 
        chmax(now, min(f[Lim][i], L[i][bg]));
    return now;
}
int main() {
    N = read(); M = read(); Lim = (1 << N) - 1;
    for(int i = 1; i <= N; i++)
        for(int j = 1; j <= M; j++) a[i][j] = read();
    Pre();
    int ans = 0;
    for(int i = 1; i <= N; i++) 
        chmax(ans, DP(i));
    cout << ans;
    return 0;
}
/*
3 2
85 6
64 71
1 83

4 2
9 9
10 8
5 3
4 3
*/