题解：
#include<iostream> #include<map> using namespace std; map<int,map<int,int>> a; int main(){ int n,q; cin>>n>>q; int k,x,y,z; for(int i=1;i<=q;i++) { scanf("%d%d%d",&k,&x,&y); if(k==1){ scanf("%d",&z); a[x][y]=z; } else{ printf("%d\n",a[x][y]); } } return 0; }
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