添加 0491.递增子序列.md C语言版本

problems/0491.递增子序列.md

@@ -313,7 +313,72 @@ var findSubsequences = function(nums) {
 
 ```
 
+C:
+```c
+int* path;
+int pathTop;
+int** ans;
+int ansTop;
+int* length;
+//将当前path中的内容复制到ans中
+void copy() {
+    int* tempPath = (int*)malloc(sizeof(int) * pathTop);
+    memcpy(tempPath, path, pathTop * sizeof(int));
+    length[ansTop] = pathTop;
+    ans[ansTop++] = tempPath;
+}
+
+//查找uset中是否存在值为key的元素
+int find(int* uset, int usetSize, int key) {
+    int i;
+    for(i = 0; i < usetSize; i++) {
+        if(uset[i] == key)
+            return 1;
+    }
+    return 0;
+}
+
+void backTracking(int* nums, int numsSize, int startIndex) {
+    //当path中元素大于1个时，将path拷贝到ans中
+    if(pathTop > 1) {
+        copy();
+    }
+    int* uset = (int*)malloc(sizeof(int) * numsSize);
+    int usetTop = 0;
+    int i;
+    for(i = startIndex; i < numsSize; i++) {
+        //若当前元素小于path中最后一位元素 || 在树的同一层找到了相同的元素，则continue
+        if((pathTop > 0 && nums[i] < path[pathTop - 1]) || find(uset, usetTop, nums[i]))
+            continue;
+        //将当前元素放入uset
+        uset[usetTop++] = nums[i];
+        //将当前元素放入path
+        path[pathTop++] = nums[i];
+        backTracking(nums, numsSize, i + 1);
+        //回溯
+        pathTop--;
+    }
+}
 
+int** findSubsequences(int* nums, int numsSize, int* returnSize, int** returnColumnSizes){
+    //辅助数组初始化
+    path = (int*)malloc(sizeof(int) * numsSize);
+    ans = (int**)malloc(sizeof(int*) * 33000);
+    length = (int*)malloc(sizeof(int*) * 33000);
+    pathTop = ansTop = 0;
+
+    backTracking(nums, numsSize, 0);
+
+    //设置数组中返回元素个数，以及每个一维数组的长度
+    *returnSize = ansTop;
+    *returnColumnSizes = (int*)malloc(sizeof(int) * ansTop);
+    int i;
+    for(i = 0; i < ansTop; i++) {
+        (*returnColumnSizes)[i] = length[i];
+    }
+    return ans;
+}
+```
 
 
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