简单题，但题意不容易理解，是求出现频度第二多的数字。
wa的原因是开始给vis数组初始话为0，而有些就该是0，却当成了没被赋值的用。
View Code #include < iostream > #include < cstdio > #include < cstdlib > #include < cstring > #include < algorithm > using namespace std; #define maxn 10008 struct XPlayer{ int id, p;} xplayer[maxn * 500 ]; int m, n; int vis[maxn]; int pcount; void input(){ pcount = 0 ; for ( int i = 0 ; i < n; i ++ ) for ( int j = 0 ; j < m; j ++ ) { int a; scanf( " %d " , & a); if (vis[a] != - 1 ) xplayer[vis[a]].p ++ ; else { xplayer[pcount].id = a; xplayer[pcount].p = 1 ; vis[a] = pcount; pcount ++ ; } }} bool operator < ( const XPlayer & a, const XPlayer & b){ if (a.p == b.p) return a.id < b.id; return a.p > b.p;} int main(){ // freopen("t.txt", "r", stdin); while (scanf( " %d%d " , & n, & m), m | n) { memset(vis, - 1 , sizeof (vis)); input(); sort(xplayer, xplayer + pcount); int i = 1 ; int temp = xplayer[ 1 ].p; while (xplayer[i].p == temp && i < pcount) { printf( " %d " , xplayer[i].id); i ++ ; } printf( " \n " ); } return 0 ;}