HDU 4975 A simple Gaussian elimination problem. Network Flow + dp on the matrix, hdugaussian

HDU 4975 A simple Gaussian elimination problem. Network Flow + dp on the matrix, hdugaussian

Random output is safe.

In the same way as hdu4888, it is feasible to run a network stream and then dp.

= N ^ 3 dp cannot pass, so change n to 200.

= Because the author did not place the problem in a matrix other than 200*200.

#include <cstdio>#include <cstring>#include <vector>#include <queue>#include <algorithm>using namespace std;const int MAX_N = 1207;const int MAX_E = MAX_N * MAX_N * 5;const int INF = 0x3f3f3f3f;struct Edge {    int v, nxt;    long long cap;    Edge() {    }    Edge(int _v, int _nxt, long long _cap) {        v = _v, nxt = _nxt, cap = _cap;    }};Edge G[MAX_E];int edgecnt, head[MAX_N];int gap[MAX_N], d[MAX_N];struct Isap {    int n, s, t;    void init(int n, int s, int t) {        this->n = n, this->s = s, this->t = t;        edgecnt = 0;        memset(head, -1, sizeof head);    }    void addedge(int u, int v, long long cap) {        G[edgecnt] = Edge(v, head[u], cap);        head[u] = edgecnt++;        G[edgecnt] = Edge(u, head[v], 0);        head[v] = edgecnt++;    }    long long dfs(int u, long long tot) {        if (u == t) return tot;        int minh = n - 1;        long long leave = tot;        for (int i = head[u]; ~i && leave; i = G[i].nxt) {            int v = G[i].v;            if (G[i].cap > 0) {                if (d[v] + 1 == d[u]) {                    long long c = dfs(v, min(leave, G[i].cap));                    G[i].cap -= c;                    G[i ^ 1].cap += c;                    leave -= c;                    if (d[s] >= n)                         return tot - leave;                }                minh = min(minh, d[v]);            }        }        if (leave == tot) {            --gap[d[u]];            if (gap[d[u]] == 0) d[s] = n;            d[u] = minh + 1;            ++gap[d[u]];        }        return tot - leave;    }    long long maxFlow() {        long long ret = 0;        memset(gap, 0, sizeof gap);        memset(d, 0, sizeof d);        gap[0] = n;        while (d[s] < n) {            ret += dfs(s, INF);        }        return ret;    }}; int n, m, k;int mat[MAX_N][MAX_N];int c[MAX_N][MAX_N];inline bool rd(int &n){        int x = 0, tmp = 1;        char c = getchar();        while((c < '0' || c > '9') && c != '-' && c != EOF) c = getchar();        if(c == EOF) return false;        if(c == '-') c = getchar(), tmp = -1;        while(c >= '0' && c <= '9') x *= 10, x += (c - '0'),c = getchar();        n = x*tmp;        return true;  }    int main() {    int T;    scanf("%d", &T);    int cas = 0;    while (T-- > 0) {        Isap ans;        scanf("%d%d", &n, &m);        k = 9;        ans.init(n + m + 2, 0, n + m + 1);        int s = 0, t = n + m + 1;        long long sum1 = 0, sum2 = 0;        for (int i = 1; i <= n; ++i) {            for (int j = 1; j <= m; ++j) {                ans.addedge(i, n + j, k);            }        }        for (int i = 1; i <= n; ++i) {            int rowSum = 0;            rd(rowSum);            sum1 += rowSum;            ans.addedge(0, i, rowSum);            }        for (int i = 1; i <= m; ++i) {            int colSum = 0;            rd(colSum);            sum2 += colSum;            ans.addedge(n + i, t, colSum);        }               int q = ans.maxFlow();        printf("Case #%d: ", ++cas);        if (sum1 != sum2 || q != sum1) puts("So naive!");        else {            int edge = 0;            n = min(n, 200);            m = min(m, 200);            for (int i = 1; i <= n; ++i) {                for (int j = 1; j <= m; ++j, edge += 2) {                    mat[i][j] = G[edge ^ 1].cap;                }            }            memset(c, false, sizeof c);            bool f = false;            for (int i = 1; i <= n; ++i) {                for (int j = 1; j <= m; ++j) {                    for (int l = j + 1; l <= m; ++l) {                        bool f1 = false, f2 = false;                        if (mat[i][j] != k && mat[i][l] != 0) {// column j could add, column l could dec                             if (c[l][j]) {                                l = m + 1, j = m + 1, i = n + 1;                                f = true;                            }                            f1 = true;                        }                        if (mat[i][j] != 0 && mat[i][l] != k) {// column l could add, column j could dec                            if (c[j][l]) {                                l = m + 1, j = m + 1, i = n + 1;                                f = true;                            }                            f2 = true;                        }                        if (f1) c[j][l] = true;                        if (f2) c[l][j] = true;                    }                }            }            if (f) puts("So young!");            else {                puts("So simple!");            }         }    }     return 0;}