add

public/c/ch2/student/ppp.c

@@ -0,0 +1,42 @@
+
+#include"stdio.h"
+#include"stdlib.h"
+int bijiao(const void* a, const void*b){
+	return (*(int*)a-*(int*)b);
+}
+int used[100];
+void dayi(int *arr,int n){
+	for(int i=0;i<n;i++){
+		printf("%d",arr[i]);
+	}
+	printf("\n");
+}
+void pailie(int *arr,int start,int end){
+	if(start==end){
+		dayi(arr,end+1);
+	}
+	else{
+		for(int i=start;i<=end;i++){
+			if(!used[i]){
+				used[i]=1;
+				int t=arr[start];
+				arr[start]=arr[i];
+				arr[i]=t;
+				pailie(arr,start+1,end);
+				t=arr[start];
+				arr[start]=arr[i];
+				arr[i]=t;
+				used[i]=0;
+			}
+		}
+	}
+}
+int main(){
+	int arr[]={1,2,3,4,3,6};
+	int size=sizeof(arr)/sizeof(arr[0]);
+    qsort(arr,size,sizeof(int),bijiao);
+	for(int i=0;i<size;i++){
+		used[i]=0;
+	}
+	pailie(arr,0,size-1);
+}