UVA - 1609 Foul Play——思路题

挺好的思路题， 题解紫书249页写的很明白，不过推荐自己先想一下

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
typedef pair<int, int> P;
const int maxn = 1300;
bool vis[maxn];
char str[maxn][maxn];
int n, a[maxn][maxn];
int cnt, pos[maxn];
vector<P> match[maxn];

int main() {
    int change[maxn];
    change[2] = 1, change[4] = 2, change[8] = 3, change[16] = 4, change[32] = 5;
    change[64] = 6, change[128] = 7, change[256] = 8, change[512] = 9, change[1024] = 10;
    while (~scanf("%d", &n)) {
        for (int i = 1; i <= n; i++) scanf("%s", str[i] + 1);
        int m = change[n];
        memset(vis, false, sizeof(vis));
        memset(a, 0, sizeof(a));
        for (int i = 0; i <= m; i++) match[i].clear();
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                a[i][j] = str[i][j] - '0';
            }
        }
        for (int k = 1; k <= m; k++) {
            //step1:
            for (int i = 1; i <= n; i++) {
                if (vis[i] || a[1][i]) continue;
                for (int j = 1; j <= n; j++) {
                    if (vis[j] || !a[j][i] || !a[1][j]) continue;
                    vis[i] = vis[j] = true;
                    match[k].push_back(make_pair(j, i));
                    break;
                }
            }
            //step2:
            for (int i = 2; i <= n; i++) {
                if (vis[i] || !a[1][i]) continue;
                match[k].push_back(make_pair(1, i));
                vis[i] = true; break;
            }
            //step3:
            cnt = 0;
            for (int i = 2; i <= n; i++) {
                if (vis[i] || a[1][i]) continue;
                pos[++cnt] = i;
            }
            for (int i = 1; i < cnt; i+=2) {
                vis[pos[i]] = vis[pos[i+1]] = true;
                if (!a[pos[i]][pos[i + 1]]) swap(pos[i], pos[i + 1]);
                match[k].push_back(make_pair(pos[i], pos[i + 1]));
            }
            //step4:
            cnt = 0;
            for (int i = 2; i <= n; i++) {
                if (!vis[i]) pos[++cnt] = i;
            }
            for (int i = 1; i <= cnt; i+=2) {
                vis[pos[i]] = vis[pos[i + 1]] = true;
                if (!a[pos[i]][pos[i+1]]) swap(pos[i], pos[i + 1]);
                match[k].push_back(make_pair(pos[i], pos[i + 1]));
            }
            //last
            for (unsigned int i = 0; i < match[k].size(); i++) {
                int index = match[k][i].first;
                vis[index] = false;
            }
        }
        for (int i = 1; i <= m; i++) {
            for (unsigned int j = 0; j < match[i].size(); j++) {
                printf("%d %d\n", match[i][j].first, match[i][j].second);
            }
        }
    }
    return 0;
}