HDU 1495 非常可乐——bfs

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <queue>using namespace std;const int maxn = 110;bool vis[maxn][maxn][maxn];int S, A, B;struct State {    int s, a, b, step;}state;queue<State> q;void solve(int &x, int X, int &y, int Y) {    if (X - x <= y) { y = y - X + x; x = X; }    else { x = x + y; y = 0; }}void add(int s, int a, int b, int step) {    if (!vis[s][a][b]) {        vis[s][a][b] = true;        q.push(State{s, a, b, step});    }}void bfs() {    int target = S>>1, ans = -1;    memset(vis, false, sizeof(vis));    vis[S][0][0] = true;    while (!q.empty()) q.pop();    q.push(State{S, 0, 0, 0});    while (!q.empty()) {        state = q.front(); q.pop();        if (state.s == target && state.a == target) { ans = state.step; break; }        int s, a, b;        s = state.s, a = state.a, b = state.b; solve(a, A, s, S); add(s, a, b, state.step + 1);        s = state.s, a = state.a, b = state.b; solve(b, B, s, S); add(s, a, b, state.step + 1);        s = state.s, a = state.a, b = state.b; solve(b, B, a, A); add(s, a, b, state.step + 1);        s = state.s, a = state.a, b = state.b; solve(s, S, a, A); add(s, a, b, state.step + 1);        s = state.s, a = state.a, b = state.b; solve(s, S, b, B); add(s, a, b, state.step + 1);        s = state.s, a = state.a, b = state.b; solve(a, A, b, B); add(s, a, b, state.step + 1);    }    if (ans == -1) printf("NO\n");    else printf("%d\n", ans);}int main() {    while (~scanf("%d %d %d", &S, &A, &B) && (S || A || B)) {        if (A < B) swap(A, B);        if (S % 2) printf("NO\n");        else bfs();    }    return 0;}